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VulnerabilityPublished Updated

CVE-2026-27192: feathersjs feathers · Origin Validation Error

Affects feathersjs feathersSource CVE Database V5

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Not known to be exploited · CVSS 7.6 High : upgrade to 5.0.40 soon.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 4.0 base score
7.6High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 19% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 5.0.40
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 21 Feb 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade feathersjs feathers to 5.0.40.

Affected software

ProductAffectedFixed in
feathersjsfeathersAffected
  • <5.0.40
Fixed in
  • 5.0.40

AI-suggested

  1. Upgrade all Feathersjs instances to version 5.0.40 or later, where the origin validation flaw is fixed.
  2. Review and tighten OAuth origin configurations to explicitly whitelist exact origins rather than relying on prefix matching.
  3. Implement additional server-side validation of the Referer and Origin headers using exact string matches or robust parsing methods rather than startsWith().
  4. Employ Content Security Policy (CSP) headers to restrict allowed sources for scripts and frames.
  5. Monitor OAuth flows for unusual origin patterns or token requests from unexpected domains.
  6. Educate users to be cautious of phishing attempts that may exploit this vulnerability.
  7. Conduct security testing and code reviews focusing on origin validation logic in custom authentication flows.

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.

References

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