CVE-2026-86099 Details
Description
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.
A path traversal vulnerability has been identified in Chainlit versions through 2.12.0. The issue arises because the application fails to properly validate the socket.io sessionId parameter provided by clients. This lack of validation allows unauthenticated attackers to manipulate the sessionId with absolute or relative path sequences, escaping the designated upload directory. Exploitation of this vulnerability could lead to the unauthorized deletion of arbitrary directories that are accessible to the service process.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 9, 2026CISA-ADP
Assessed Sep 9, 2026References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-22 | Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Chainlit | <= 2.12.0 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 9, 2026 | CVE Modified | CISA-ADP |
| Sep 9, 2026 | New CVE Received | [email protected] |