SEPTEMBER 15, 2026
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Case File

CVE-2026-86099

HIGH · CVSS 8.2 EPSS 0.39% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-09-09 · Last synced 2026-09-15

CyberRota Analysis

AI-Generated

The vulnerability allows unauthenticated attackers to manipulate the socket.io sessionId parameter, leading to potential filesystem traversal and arbitrary directory deletion. This poses a significant risk to any service utilizing affected versions of Chainlit, particularly those with sensitive data or critical infrastructure. Organizations using Chainlit should prioritize patching to mitigate the risk of exploitation.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-86099
Severity
HIGH
CVSS
8.2
EPSS
0.39%

Original NVD 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.