{"id":"CVE-2026-56104","aliases":["GHSA-c39v-8hrw-h448"],"title":"Chainlit contains a session hijacking vulnerability","summary":"Chainlit contains a session hijacking vulnerability","severity":"high","cvss":7.4,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","vendor":"chainlit","product":"chainlit","ecosystem":"pip","affected":["chainlit < 2.10.1"],"patched":["chainlit 2.10.1"],"published":"2026-06-22","updated":"2026-09-21","sourceUpdated":"2026-09-21T22:30:12.894277651Z","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-c39v-8hrw-h448","references":[{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-56104"},{"url":"https://github.com/Chainlit/chainlit/pull/2857"},{"url":"https://github.com/Chainlit/chainlit/commit/5effb664f1e0af4a4f0a42fe63ea979676039a7f"},{"url":"https://github.com/Chainlit/chainlit"},{"url":"https://github.com/Chainlit/chainlit/releases/tag/2.10.1"},{"url":"https://www.vulncheck.com/advisories/chainlit-session-hijacking-via-websocket-session-restoration"},{"url":"https://github.com/advisories/GHSA-c39v-8hrw-h448"}],"tags":["osv","pip","ghsa"],"epss":0.00417,"epssPercentile":0.35662,"cwe":["CWE-862"],"ingestedAt":"2026-09-21T22:54:37.976Z","slug":"CVE-2026-56104","body":"## Overview\n\nChainlit 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.\n\n## Affected packages\n\n- `chainlit < 2.10.1`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `chainlit 2.10.1`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":40.7,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":208906,"id":"CVE-2026-56104","ts":1790061351639,"field":"severity","old":"critical","new":"high"}]}