CVE-2026-34959

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 4.0

5.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N

CVSS 3.1

4.7CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 21% of CVEs (scores of 2026-10-25)

CWE

CWE-20

Published

2026-08-25

Modified

2026-10-12

Record from

the NVD, synced 2026-10-19

References

• https://github.com/vrana/adminer/security/advisories/GHSA-8478-xrj3-h9c2
• https://www.vulncheck.com/advisories/adminer-before-open-redirect-via-x-forwarded-prefix
• https://github.com/vrana/adminer/security/advisories/GHSA-8478-xrj3-h9c2

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