CVE-2026-16434Adminer before 5.5.1 X-Forwarded-Prefix Backslash Bypass
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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Adminer 4.6.0 through 5.5.0 (fixed in 5.5.1) contains an incomplete fix for a prior X-Forwarded-Prefix vulnerability (GHSA-8478-xrj3-h9c2). The validation guard (bootstrap.inc.php) only rejects prefixes matching ^/[^/], blocking //evil.com but allowing values such as /\evil.com whose second character is a backslash. Because browsers normalize backslash to forward slash, a network-path reference survives into REQUEST_URI and reaches cookie_path(), affecting the Set-Cookie Path attribute. Exploitation requires that clients can set the X-Forwarded-Prefix header (a misconfigured or absent reverse proxy). Impact is limited to anomalous cookie-path scoping.
- CVSS
- 2.3 LOW (v4.0, CNA)CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
- Weakness (CWE)
- CWE-20
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- VulnCheck
- NVD analysis
- Deferred
- Record last updated
- Aug 27, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
vrana adminer vrana:adminer (from the name) | before 5.5.1; 5.5.1 not affected | CNA record |
References
- https://github.com/vrana/adminer/security/advisories/GHSA-fr74-9mf9-gf44vendor-advisory
- https://www.vulncheck.com/advisories/adminer-before-x-forwarded-prefix-backslash-bypassthird-party-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.