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CVE-2026-39963

CVE-2026-39963 · Serendipity: Host Header Injection enables authentication cookie scoping to an attacker-controlled domain

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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 6.9 · Medium · EPSS 0.2% · Fix available

Published
Updated

Stack: php

Affected products and versions

  • serendipity

    Versions
    • < 2.6.0: Affected

    No fix published

  • s9y/serendipity Packagist

    Versions
    • 2.0.0
    • 2.0.1
    • 2.0.2
    • 2.0.3
    • 2.0.4
    • 2.0.5
    • 2.1-beta1
    • 2.1-beta2
    • 2.1-beta3
    • 2.1-rc1
    • 2.1.0
    • 2.1.1
    • 2.1.2
    • 2.1.3
    • 2.1.4
    • 2.1.5
    • 2.1.6
    • 2.2.1-alpha1
    • 2.3-beta1
    • 2.3-rc1
    • 2.3.0
    • 2.3.1
    • 2.3.2
    • 2.3.3
    • 2.3.4
    • 2.3.5
    • 2.4-beta1
    • 2.4.0
    • 2.5-beta1
    • 2.5.0
    • 2.6-beta1
    Affected ranges
    • ECOSYSTEM: < 2.6.0

    Update to 2.6.0

Original sources

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