CVE-2026-56104

critical

Description

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.

References

https://www.vulncheck.com/advisories/chainlit-session-hijacking-via-websocket-session-restoration

https://github.com/Chainlit/chainlit/releases/tag/2.10.1

https://github.com/Chainlit/chainlit/pull/2857

https://github.com/Chainlit/chainlit/commit/5effb664f1e0af4a4f0a42fe63ea979676039a7f

Details

Source: Mitre, NVD

Published: 2026-06-22

Updated: 2026-06-22

Risk Information

CVSS v2

Base Score: 7.1

Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:N

Severity: High

CVSS v3

Base Score: 7.4

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Severity: High

CVSS v4

Base Score: 9.1

Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Severity: Critical