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CVE-2026-120492VulnerabilityPublished

Chainlit 2.12.0 contains a server-side request forgery vulnerability that allows unauthenticated attackers to bypass

Source GCVE Database

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Authoritative record:CVE-2026-120492· Medium 6.3

Not known to be exploited · CVSS 6.3 Medium.

Data as of 2 Nov 2026, 16:43 UTC

CVSS 4.0 base score
6.3Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (VulnCheck)CVSS 4.06.3
CNA (VulnCheck)CVSS 3.15.4
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 2 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
ChainlitChainlitAffected
  • =2.12.0
Fixed in–
PyPIChainlitpkg:pypi/ChainlitOther threatsAffected
  • =2.12.0
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

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