Vulnerability · Published Aug 25, 2026 · Assigned by VulnCheck
CVE-2026-34959Adminer before 5.5.0 Open Redirect via X-Forwarded-Prefix
Medium 4.7
In plain English
A medium-severity improper input validation in adminer from vrana. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 22% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | adminer | no fix listed | DEBIAN-CVE-2026-34959 |
| Debian:13 | adminer | no fix listed | DEBIAN-CVE-2026-34959 |
| Debian:14 | adminer | 6.0.0-1 | DEBIAN-CVE-2026-34959 |
| Ubuntu:22.04:LTS | adminer | no fix listed | UBUNTU-CVE-2026-34959 |
| Ubuntu:24.04:LTS | adminer | no fix listed | UBUNTU-CVE-2026-34959 |
| Ubuntu:26.04:LTS | adminer | no fix listed | UBUNTU-CVE-2026-34959 |
Affected products (as reported)
Weakness: CWE-20 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
References
- GitHub Security Advisory (GHSA-8478-xrj3-h9c2) vendor-advisory
- VulnCheck Advisory: Adminer before 5.5.0 Open Redirect via X-Forwarded-Prefix third-party-advisory