CVE-2026-56104: Chainlit

High severity, CVSS 8.2. EPSS: 0.4% chance of exploitation in the next 30 days.

Chainlit before 2.10.1 contains a session hijacking vulnerability that allows unauthenticated attackers to restore and inherit authenticated user sessions by presenting a valid sessionId during WebSocket session restoration without ownership verification. Attackers can exploit the restore_existing_session path to assume a victim's permissions and roles, enabling unauthorized invocation of tools and access to data restricted to the authenticated victim.

Affected products

• Chainlit Chainlit: before 2.10.1 (fixed in 2.10.1)

Published 2026-06-22. Last modified 2026-10-08.