CVE-2026-27192
HIGH
GHSA-mp4x-c34x-wv3x
CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
3Tags
Description
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.
Analysis
Origin validation bypass in Feathers framework versions 5.0.39 and below allows remote attackers to hijack OAuth tokens by registering domains with a common prefix to legitimate allowed origins, exploiting insufficient string comparison in the getAllowedOrigin() function. An attacker can craft a domain like https://target.com.attacker.com to bypass validation configured for https://target.com and intercept authentication credentials. …
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Remediation
Within 24 hours: inventory all systems running Feathersjs and assess exposure level; prioritize production instances. Within 7 days: apply the available vendor patch to all affected systems in development and staging environments and conduct functional testing. …
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External POC / Exploit Code
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