GHSA-RV95-896H-C2VC

Vulnerability from github – Published: 2024-03-25 19:40 – Updated: 2025-07-21 16:57
VLAI?
Summary
Express.js Open Redirect in malformed URLs
Details

Impact

Versions of Express.js prior to 4.19.2 and pre-release alpha and beta versions before 5.0.0-beta.3 are affected by an open redirect vulnerability using malformed URLs.

When a user of Express performs a redirect using a user-provided URL Express performs an encode using encodeurl on the contents before passing it to the location header. This can cause malformed URLs to be evaluated in unexpected ways by common redirect allow list implementations in Express applications, leading to an Open Redirect via bypass of a properly implemented allow list.

The main method impacted is res.location() but this is also called from within res.redirect().

Patches

https://github.com/expressjs/express/commit/0867302ddbde0e9463d0564fea5861feb708c2dd https://github.com/expressjs/express/commit/0b746953c4bd8e377123527db11f9cd866e39f94

An initial fix went out with express@4.19.0, we then patched a feature regression in 4.19.1 and added improved handling for the bypass in 4.19.2.

Workarounds

The fix for this involves pre-parsing the url string with either require('node:url').parse or new URL. These are steps you can take on your own before passing the user input string to res.location or res.redirect.

References

https://github.com/expressjs/express/pull/5539 https://github.com/koajs/koa/issues/1800 https://expressjs.com/en/4x/api.html#res.location

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": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "express"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.19.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "express"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.0.0-alpha.1"
            },
            {
              "fixed": "5.0.0-beta.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2024-29041"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1286",
      "CWE-601"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2024-03-25T19:40:26Z",
    "nvd_published_at": "2024-03-25T21:15:46Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nVersions of Express.js prior to 4.19.2 and pre-release alpha and beta versions before 5.0.0-beta.3 are affected by an open redirect vulnerability using malformed URLs.\n\nWhen a user of Express performs a redirect using a user-provided URL Express performs an encode [using `encodeurl`](https://github.com/pillarjs/encodeurl) on the contents before passing it to the `location` header. This can cause malformed URLs to be evaluated in unexpected ways by common redirect allow list implementations in Express applications, leading to an Open Redirect via bypass of a properly implemented allow list.\n\nThe main method impacted is `res.location()` but this is also called from within `res.redirect()`.\n\n### Patches\n\nhttps://github.com/expressjs/express/commit/0867302ddbde0e9463d0564fea5861feb708c2dd\nhttps://github.com/expressjs/express/commit/0b746953c4bd8e377123527db11f9cd866e39f94\n\nAn initial fix went out with `express@4.19.0`, we then patched a feature regression in `4.19.1` and added improved handling for the bypass in `4.19.2`.\n\n### Workarounds\n\nThe fix for this involves pre-parsing the url string with either `require(\u0027node:url\u0027).parse` or `new URL`. These are steps you can take on your own before passing the user input string to `res.location` or `res.redirect`.\n\n### References\n\nhttps://github.com/expressjs/express/pull/5539\nhttps://github.com/koajs/koa/issues/1800\nhttps://expressjs.com/en/4x/api.html#res.location",
  "id": "GHSA-rv95-896h-c2vc",
  "modified": "2025-07-21T16:57:31Z",
  "published": "2024-03-25T19:40:26Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/expressjs/express/security/advisories/GHSA-rv95-896h-c2vc"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-29041"
    },
    {
      "type": "WEB",
      "url": "https://github.com/koajs/koa/issues/1800"
    },
    {
      "type": "WEB",
      "url": "https://github.com/expressjs/express/pull/5539"
    },
    {
      "type": "WEB",
      "url": "https://github.com/expressjs/express/commit/0867302ddbde0e9463d0564fea5861feb708c2dd"
    },
    {
      "type": "WEB",
      "url": "https://github.com/expressjs/express/commit/0b746953c4bd8e377123527db11f9cd866e39f94"
    },
    {
      "type": "WEB",
      "url": "https://expressjs.com/en/4x/api.html#res.location"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/expressjs/express"
    }
  ],
  "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"
    }
  ],
  "summary": "Express.js Open Redirect in malformed URLs"
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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