CVE-2026-120492Medium· 5.4▾ TwilightPoC availableChainlit 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 sub…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 29.7 · likelihood 0 · exploitation 12
A public proof-of-concept already exists for this vulnerability — see Exploit availability below.
Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the assigning CNA record, not NVD.
Exploit-prediction probability, daily snapshots since Nov 3.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
0.2%
Last analysed / modified upstream
Exploit / PoC code exists
7.2 → 5.4
high → medium
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.
Chainlit 2.12.0Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Affected packages:
chainlit >= 2.4.0rc0, < 2.12.0Patched in:
chainlit 2.12.0Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
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