CVE-2026-39963
Last modified
CVE-2026-39963 is a medium-severity vulnerability rated 6.9/10 on the CVSS scale. 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(). EPSS estimates a 0.22% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N
Weakness Enumeration
Affected Software
| Vendor | Product | Versions | Update |
|---|---|---|---|
| S9y | Serendipity | < 2.6.0 | — |
| S9y | Serendipity | 2.6.0 | Beta1 |
References
- https://github.com/s9y/Serendipity/security/advisories/GHSA-4m6c-649p-f6gfExploit, Mitigation, Vendor Advisory
- https://github.com/s9y/Serendipity/security/advisories/GHSA-4m6c-649p-f6gfExploit, Mitigation, Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
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