CVE-2026-27192
highpriority · track · 32EPSS 0.003 · 19 %ileEUUSEPSS · scored 2026-10-27
Feathersjs is a framework for creating web APIs and real-time applications with TypeScript or JavaScript. In versions 5.0.39 and below, 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, and 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. This issue has bee fixed in version 5.0.40.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4.9–8.1
ssvc
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weaknesses
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affected products (3)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- GHSA-mp4x-c34x-wv3xFeathers has an origin validation bypass via prefix matching2026-02-19ghsa · osvUS
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: ```javascript // 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.
also known as (3)
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sources
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references (10)
External citations — patches, advisories, analysis.
- https://feathersjs.com/Patchcnnvd
- https://github.com/feathersjs/feathers/commit/ee19a0ae9bc2ebf23b1fe598a1f7361981b65401cnnvd
- https://github.com/feathersjs/feathers/releases/tag/v5.0.40cnnvd
- https://github.com/feathersjs/feathers/security/advisories/GHSA-mp4x-c34x-wv3xcnnvd
- https://github.com/feathersjs/feathers/commit/ee19a0ae9bc2ebf23b1fe598a1f7361981b65401enisa_euvd
- https://github.com/feathersjs/feathers/releases/tag/v5.0.40enisa_euvd
- https://github.com/feathersjs/feathers/security/advisories/GHSA-mp4x-c34x-wv3xenisa_euvd
- https://github.com/feathersjs/feathers/commit/ee19a0ae9bc2ebf23b1fe598a1f7361981b65401Patchnvd
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