CVE-2026-56706: Adminer before 5.4.3 CSRF Token Secret Recovery via XOR Masking
Adminer before 5.4.3 uses a CSRF token scheme that transmits both the XOR mask and the masked value in every token (format (rand XOR secret):rand), allowing anyone who observes a single CSRF token (e.g., via network sniffing, log files, Referrer header, or XSS) to recover the session secret with a single XOR operation and forge unlimited valid tokens. The implementation is further weakened by a low-entropy session token (rand(1,1e6), ~20 bits) that permits blind brute-force, and by use of loose comparison (==) in token verification, enabling PHP type juggling. Exploitation enables cross-site request forgery against authenticated sessions, including execution of arbitrary SQL queries.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 5.4.3 - Configuration
Update Adminer’s CSRF token verification logic to use strict comparison (===) rather than loose comparison (==) to prevent PHP type juggling from bypassing validation.
Adminer CSRF token verification = Use strict comparison (===) instead of loose comparison (==) - Compensating control
Assume captured CSRF tokens may allow forging; monitor for suspicious cross-site requests/abnormal admin actions and restrict access where possible (e.g., limit exposure of the Adminer interface to trusted networks/users) until fixed.