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TI-2026-13735 Aliases CVE-2026-16434GHSA-jh7j-hfxx-jv6m

Adminer before 5.5.1 X-Forwarded-Prefix Backslash Bypass

Priority MEDIUM 51CWE-20Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Passive
Attack complexity
High
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
None · Low · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00389 33rd percentileScored 2026-11-07
Fix Fixed adminer (vrana): 5.5.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
Admineradminerbefore 5.5.15.5.1Patch availableCNA
  • adminer VendorAdminer Affected before 5.5.1 Fixed in 5.5.1 Patch available CNA

Remediation

  • Fix · CNA adminer (vrana) Fixed in 5.5.1

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-16434
  2. 2026-10-03 Alias added: GHSA-jh7j-hfxx-jv6m

References

Advisory 1

  • TI-2021-04411 SSRF in adminer KEVCVSS 3.1HIGH 7.2
  • TI-2026-40884 Adminer before 5.4.3 Remote Code Execution via MSSQL PDO DSN Injection CVSS 4.0CRITICAL 9.3
  • TI-2026-71163 Remote code execution in Adminer via UTF-8 BOM SQLite bypass CVSS 4.0HIGH 8.6
  • TI-2026-40882 Adminer before 5.4.3 Remote Code Execution via SQLite VACUUM INTO CVSS 4.0HIGH 8.6
  • TI-2026-64854 Adminer before 6.0.2 Privileged-Port SSRF via host_port Regex CVSS 4.0MEDIUM 6.9
  • TI-2026-64852 Adminer before 6.0.2 Unauthenticated SSRF via Elasticsearch Driver CVSS 4.0MEDIUM 6.9
See all 26 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences