CVE-2026-86099

Chainlit through 2.12.0 fails to validate the client-supplied socket.io sessionId parameter, allowing unauthenticated attackers to traverse filesystem paths by injecting absolute or relative path sequences. Attackers can craft malicious sessionId values that escape the upload directory and recursively delete arbitrary directories accessible to the service process.

CVSS v3 8.2 HIGH

8.2^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 4.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/Chainlit/chainlit
https://github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/session.py
https://github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/socket.py
https://pypi.org/project/chainlit/
https://www.vulncheck.com/advisories/chainlit-through-2.12.0-path-traversal-via-socket-io-sessionid

Configurations

No configuration.

History

No history.

Information

Published : 2026-09-09 14:17

Updated : 2026-09-09 20:20

NVD link : CVE-2026-86099

Mitre link : CVE-2026-86099

CVE.ORG link : CVE-2026-86099

JSON object : View

Products Affected

No product.

CWE

CWE-22

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

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