CVE-2026-56104
Chainlit < 2.10.1 Session Hijacking via WebSocket Session Restoration
- State
- Published
- Severity
- 8.8 High
- Published
- Jun 22, 2026
- Updated
- Oct 8, 2026
- Reserved
- Jun 18, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.8 High | CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N | VulnCheck |
| 3.1 | 8.2 High | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N | VulnCheck |
Weaknesses
- CWE-862 Missing Authorization
Affected Products
| Product | Versions |
|---|---|
chainlitChainlit |
|
References
- Release Notesrelease-notes
- Pull Requestissue-tracking
- Patch Commitpatch
- https://www.vulncheck.com/advisories/chainlit-session-hijacking-via-websocket-session-restorationthird-party-advisory
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