CVE-2026-27192
Feathers has an origin validation bypass via prefix matching
Description
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.
How to fix CVE-2026-27192
To remediate CVE-2026-27192, upgrade the affected package to a fixed version below.
- —upgrade to 5.0.40 or later
Is CVE-2026-27192 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 5.0.40
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | 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 |