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.
This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 6.9, indicating it can be exploited remotely over the network but requires specific conditions to be met though user interaction is required and does not require pre-existing privileges . The vulnerability impacts confidentiality (data exposure), limited integrity, for affected systems. Impacting 1 product from s9y organizations running these solutions should prioritize assessment and patching.
Reported in 2026, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.
2026-04-15T04:17:39.580
2026-10-26T22:10:00.163
Analyzed
CVSSv3.1: 6.9 (MEDIUM)
| Type | Vendor | Product | Version/Range | Vulnerable? |
|---|---|---|---|---|
| Application | s9y | serendipity | < 2.6.0 | Yes |
| Application | s9y | serendipity | 2.6.0 | Yes |
SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For s9y's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.