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CVE-2026-39963

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CVE-2026-39963

Published: Apr 14, 2026

Modified: Apr 15, 2026

PUBLISHED

CVSS v3.1

6.9

MEDIUM

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.

VendorProductVersions

s9y

Serendipity

affected
< 2.6.0

Weaknesses (CWE)

CWE-565

CVSS v3.1 Details

CVSS v3.1 Vector

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

References

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