Vulnerability Description
Adminer 4.6.0 before 5.5.0 prepends the client-supplied X-Forwarded-Prefix header to $_SERVER["REQUEST_URI"] with no trusted-proxy check and no validation of the prefix value. An attacker can supply an absolute URL (e.g. X-Forwarded-Prefix: https://evil.example) that flows into Location redirect headers, the Set-Cookie path attribute, and self-referential links. This enables an authenticated open redirect after state-changing POSTs, unauthenticated control of the session cookie path attribute, and poisoning of self-referential links; CR/LF cannot be injected, so header splitting/XSS is not possible.
CVSS Score
MEDIUM
Related Weaknesses (CWE)
References
- https://github.com/vrana/adminer/security/advisories/GHSA-8478-xrj3-h9c2
- https://www.vulncheck.com/advisories/adminer-before-open-redirect-via-x-forwarde
- https://github.com/vrana/adminer/security/advisories/GHSA-8478-xrj3-h9c2
FAQ
What is CVE-2026-34959?
CVE-2026-34959 is a vulnerability with a CVSS score of 4.7 (MEDIUM). Adminer 4.6.0 before 5.5.0 prepends the client-supplied X-Forwarded-Prefix header to $_SERVER["REQUEST_URI"] with no trusted-proxy check and no validation of the prefix value. An attacker can supply a...
How severe is CVE-2026-34959?
CVE-2026-34959 has been rated MEDIUM with a CVSS base score of 4.7/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-34959?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.