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CVE-2026-120492

6.3 mediumEPSS 0.2%

Medium (6.3). EPSS 0.2% estimated probability of exploitation activity in the next 30 days. Fixed in chainlit 2.12.0.

On this page
Chainlit 2.12.0 contains a server-side request forgery vulnerability that allows unauthenticated attackers to bypass path-scoped MCP allowed_urls entries because validate_mcp_url does not reject the semicolon character. Attackers can submit MCP URLs with '..;' segments to the /mcp endpoint, causing requests to paths outside the operator's grant on origins that strip semicolon path parameters.

Severity

CVSS 4.0

6.3 medium
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

CVSS 3.1

5.4 medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
EPSS
0.2% estimated probability of exploitation activity in the next 30 days; 13th percentile. Scored 2026-11-04. A forecast for this CVE across the internet, not for your own systems.
CWE
CWE-918 Server-Side Request Forgery (SSRF)
OWASP Top 10
A01:2025 Broken Access Control
Published
Modified
Record from
the NVD, synced

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Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
GHSA-hvfh-5mj3-5f3jPyPIchainlit>=2.4.0rc0 <2.12.02.12.0
PYSEC-2026-3811PyPIchainlit>=2.4.0rc0 <2.12.02.12.0

Attack patterns (CAPEC)

  • CAPEC-664 Server Side Request Forgery Likelihood: High · Severity: High

The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.

References

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