Reliance on Cookies without Validation and Integrity Checking Affecting s9y/serendipity package, versions <2.6.0
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applications- Snyk IDSNYK-PHP-S9YSERENDIPITY-16109573
- published19 Apr 2026
- disclosed14 Apr 2026
- creditmabjr33
Introduced: 14 Apr 2026
NewCVE-2026-39963 (opens in a new tab)How to fix?
Upgrade s9y/serendipity to version 2.6.0 or higher.
Overview
Affected versions of this package are vulnerable to Reliance on Cookies without Validation and Integrity Checking via the serendipity_setCookie function. An attacker can cause authentication cookies, including session and auto-login tokens, to be scoped to an attacker-controlled domain by manipulating the Host header during the login process, potentially leading to session hijacking, token leakage, or privilege escalation.