Chainlit contains a session hijacking vulnerability
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 software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | chainlit | < 2.10.1 | 2.10.1 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-56104
- https://github.com/Chainlit/chainlit/pull/2857
- https://github.com/Chainlit/chainlit/commit/5effb664f1e0af4a4f0a42fe63ea979676039a7f
- https://github.com/Chainlit/chainlit
- https://github.com/Chainlit/chainlit/releases/tag/2.10.1
- https://www.vulncheck.com/advisories/chainlit-session-hijacking-via-websocket-session-restoration
- https://pypi.org/project/chainlit
- https://github.com/advisories/GHSA-c39v-8hrw-h448
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N- Weakness (CWE)
CWE-862- Platform
- Python (PyPI)
- Package
chainlit- Disclosed
- 22.06.2026
- Updated
- 11.10.2026 15:18
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2026-4028 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-c39v-8hrw-h448 - CC BY 4.0
Vulnerability history: chainlit
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 6
- First → latest
- 01.2026 08.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 2
- High 2
- Medium 1
- Low 1
Disclosures per year
- 2026: 6
-
Chainlit contains a session hijacking vulnerability this entry
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