Serendipity is a PHP-powered weblog engine. In versions 2.6-beta2 and below, the serendipity_setCookie() function in include/functions_config.inc.php uses $_SERVER['HTTP_HOST'] without validation as the domain parameter of setcookie(). An attacker who can influence the Host header at login time, such as via MITM, reverse proxy misconfiguration, or load balancer manipulation, can force authentication cookies including session tokens and auto-login tokens to be scoped to an attacker-controlled domain. This enables session fixation, token leakage to attacker-controlled infrastructure, and privilege escalation if an admin logs in under a poisoned Host header. This issue has been fixed in version 2.6.0.
Fix
Patch, vendor advisory and mitigation references on NVD 2
- https://github.com/s9y/Serendipity/security/advisories/GHSA-4m6c-649p-f6gf Exploit, Mitigation, Vendor Advisory
- https://github.com/s9y/Serendipity/security/advisories/GHSA-4m6c-649p-f6gf Exploit, Mitigation, Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 6.9 · s9yNVD modified 2026-10-26 22:10
Affected (CPE criteria) 2
cpe:2.3:a:s9y:serendipity:*:*:*:*:*:*:*:*cpe:2.3:a:s9y:serendipity:2.6.0:beta1:*:*:*:*:*:*
References 3
- https://github.com/s9y/Serendipity/releases/tag/2.6.0 Product
- https://github.com/s9y/Serendipity/security/advisories/GHSA-4m6c-649p-f6gf Exploit, Mitigation, Vendor Advisory
- https://github.com/s9y/Serendipity/security/advisories/GHSA-4m6c-649p-f6gf Exploit, Mitigation, Vendor Advisory