Chainlit 2.12.0 contains a server-side request forgery vulnerability that allows unauthenticated attackers to bypass
Source GCVE Database
Not known to be exploited · CVSS 6.3 Medium.
Data as of 2 Nov 2026, 16:43 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 6.3 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 5.4 |
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 2 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| ChainlitChainlit | Affected
| Fixed in– |
PyPIChainlitpkg:pypi/ChainlitOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Until a fix is available, restrict access to the /mcp endpoint and monitor for suspicious requests containing semicolon characters in URLs. Avoid exposing the service to untrusted networks if possible.
Description
Chainlit version 2.12.0 has a server-side request forgery (SSRF) vulnerability that allows unauthenticated attackers to bypass path-scoped MCP allowed_urls restrictions. This occurs because the validate_mcp_url function does not reject semicolon characters, enabling attackers to craft MCP URLs with '..;' path segments. These specially crafted requests to the /mcp endpoint can access paths outside the intended operator's grant on origins that strip semicolon path parameters.
References
- github.com/Chainlit/chainlit/security/advisories/GHSA-hvfh-5mj3-5f3j (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-120492 (opens in a new tab)
- github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/mcp.py (opens in a new tab)
- github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/mcp.py (opens in a new tab)
- vulncheck.com/advisories/chainlit-2.12.0-ssrf-via-semicolon-path-segment-in-mcp-allowed-urls (opens in a new tab)