CVE-2026-56104

Chainlit < 2.10.1 Session Hijacking via WebSocket Session Restoration

Published Jun 22, 2026 CVSS 4.0 · 8.8 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-c39v-8hrw-h448 Chainlit contains a session hijacking vulnerability
History
Type Values Removed Values Added
CPEs cpe:2.3:a:chainlit:chainlit:*:*:*:*:*:*:*:*
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}

cvssV4_0

{'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'}

cvssV3_1

{'score': 8.2, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N'}

cvssV4_0

{'score': 8.8, 'vector': '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'}

Type Values Removed Values Added
First Time appeared Chainlit
Chainlit chainlit
Vendors & Products Chainlit
Chainlit chainlit
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Chainlit < 2.10.1 Session Hijacking via WebSocket Session Restoration
Weaknesses CWE-862
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}

cvssV4_0

{'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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Nov 8, 2026, 2:05 PM
Reserved
Jun 18, 2026, 7:15 PM
Status
Deferred
Published
Jun 22, 2026, 4:16 PM
Modified
Oct 8, 2026, 4:17 PM