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CVE-2026-39963GHSA-4M6C-649P-F6GF

Serendipity: Host Header Injection enables authentication cookie scoping to an attacker-controlled domain

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 2.6.0
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: poc
  • Automatable: no
  • Technical impact: partial

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: poc · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • s9y Serendipity

    fixed in 2.6.0

  • s9y/serendipityPackagist

    fixed in 2.6.0

References 2

GitHub · s9y/Serendipity