Improper input validation in Vrana Adminer
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.
Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.7 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (19.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 20th percentile — 19.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
Weakness classification (CWE)
References
- github.com/vrana/adminer/security/advisories/GHSA-8478-xrj3-h9c2 (vendor-advisory)
- www.vulncheck.com/advisories/adminer-before-open-redirect-via-x-forwarded-prefix (third-party-advisory)
Frequently asked questions
- What is CVE-2026-34959?
- CVE-2026-34959 is a medium-severity vulnerability in Vrana Adminer, classified under Improper Input Validation. CVSS score: 4.7/10. Published 2026-08-25.
- How severe is CVE-2026-34959?
- Medium severity. CVSS v3 base score is 4.7 out of 10.