CVE-2026-39963
Description
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.
CVSS Details
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N Threat Intelligence
Weaknesses 1
Affected Products 2
References 2
- github.com https://github.com/s9y/Serendipity/releases/tag/2.6.0
- github.com https://github.com/s9y/Serendipity/security/advisories/GHSA-4m6c-649p-f6gf
Remediation
No remediation data recorded yet
Check vendor advisories and the NVD entry for patch availability.