CVE-2016-4309: Session fixation vulnerability in Symphony CMS 2.6.7, when session.use_only_cookies is disabled, allows rem...

Security readout for executives and security teams

CVE-2016-4309 affects Symphony CMS 2.6.7 when PHP is configured to accept session IDs outside cookies. An attacker could cause a victim to use a known PHPSESSID and later take over that web session. Business impact depends on whether the site is internet-facing and uses the risky PHP session setting. Likely exposure is limited to Symphony CMS 2.6.7 deployments where PHP session.use_only_cookies is disabled. Internet-facing admin or authenticated areas raise concern. The source bundle lists affected vendor and product metadata as n/a, so organizations should confirm exposure through asset inventory and configuration review. Prioritize within normal vulnerability remediation cycles unless the affected Symphony CMS site protects sensitive data or administrative functions. Escalate if internet-facing deployments match the risky PHP configuration. There is public exploit information, but no supplied evidence of active exploitation. Mitigation focus: Check vendor guidance and apply the upstream Symphony CMS fix or supported update.; Enable PHP session.use_only_cookies where compatible with the application.; Review session handling settings across all Symphony CMS hosts..

Prepared

Jun 13, 2026, 14:22 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.