CVE-2026-39963

MEDIUM EPSS 13.0%
Published Apr 15, 20262mo ago · Modified Jun 17, 20262w ago
6.9 CVSS 3.1
Medium
Find Similar
Published Apr 15, 2026 2mo ago
Last Modified Jun 17, 2026 2w ago

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

Base Score
6.9
Exploitability
1.6
Impact
4.7
Vector string
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N
Attack Vector Network
Attack Complexity High
Privileges Required None
User Interaction Required
Scope Changed
Confidentiality High
Integrity Low
Availability None

Threat Intelligence

EPSS Exploit Probability
13.0% percentile
Exploit & Patch Status
Public Exploit Known
No Patch Available

Weaknesses 1

CWE-565

Affected Products 2

VendorProductVersionRange
s9yserendipity* <2.6.0
s9yserendipity2.6.0any

References 2

  • github.com https://github.com/s9y/Serendipity/releases/tag/2.6.0
    Product
  • github.com https://github.com/s9y/Serendipity/security/advisories/GHSA-4m6c-649p-f6gf
    ExploitMitigationVendor Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.