GHSA-MP4X-C34X-WV3X

Vulnerability from github – Published: 2026-02-19 20:32 – Updated: 2026-02-19 20:32
VLAI?
Summary
Feathers has an origin validation bypass via prefix matching
Details

The origin validation uses startsWith() for comparison, allowing attackers to bypass the check by registering a domain that shares a common prefix with an allowed origin.

The getAllowedOrigin() function checks if the Referer header starts with any allowed origin:

// https://github.com/feathersjs/feathers/blob/dove/packages/authentication-oauth/src/strategy.ts#L75
const allowedOrigin = origins.find((current) => referer.toLowerCase().startsWith(current.toLowerCase()));

This comparison is insufficient as it only validates the prefix. This is exploitable when the origins array is configured and an attacker registers a domain starting with an allowed origin string (e.g., https://target.com.attacker.com bypasses https://target.com).

On its own, tokens are still redirected to a configured origin. However, in specific scenarios an attacker can initiate the OAuth flow from an unauthorized origin and exfiltrate tokens, achieving full account takeover.

Credits: Abdelwahed Madani Yousfi (@vvxhid) / Edoardo Geraci (@b0-n0-b0) / Thomas Rinsma (@ThomasRinsma) From Codean Labs.

Severity ?
7.6 (High)
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 5.0.39"
      },
      "package": {
        "ecosystem": "npm",
        "name": "@feathersjs/authentication-oauth"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.0.40"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-27192"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-346"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-19T20:32:28Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "The origin validation uses `startsWith()` for comparison, allowing attackers to bypass the check by registering a domain that shares a common prefix with an allowed origin.\n\nThe `getAllowedOrigin()` function checks if the Referer header starts with any allowed origin:\n```javascript\n// https://github.com/feathersjs/feathers/blob/dove/packages/authentication-oauth/src/strategy.ts#L75\nconst allowedOrigin = origins.find((current) =\u003e referer.toLowerCase().startsWith(current.toLowerCase()));\n```\n\nThis comparison is insufficient as it only validates the prefix. This is exploitable when the `origins` array is configured and an attacker registers a domain starting with an allowed origin string (e.g., `https://target.com.attacker.com` bypasses `https://target.com`).\n\nOn its own, tokens are still redirected to a configured origin. However, in specific scenarios an attacker can initiate the OAuth flow from an unauthorized origin and exfiltrate tokens, achieving full account takeover.\n\n**Credits**:  Abdelwahed Madani Yousfi (@vvxhid) / Edoardo Geraci (@b0-n0-b0) / Thomas Rinsma (@ThomasRinsma) From Codean Labs.",
  "id": "GHSA-mp4x-c34x-wv3x",
  "modified": "2026-02-19T20:32:29Z",
  "published": "2026-02-19T20:32:28Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/feathersjs/feathers/security/advisories/GHSA-mp4x-c34x-wv3x"
    },
    {
      "type": "WEB",
      "url": "https://github.com/feathersjs/feathers/commit/ee19a0ae9bc2ebf23b1fe598a1f7361981b65401"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/feathersjs/feathers"
    },
    {
      "type": "WEB",
      "url": "https://github.com/feathersjs/feathers/releases/tag/v5.0.40"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Feathers has an origin validation bypass via prefix matching"
}


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