CVE-2026-120492

Chainlit 2.12.0 SSRF via Semicolon Path Segment in MCP allowed_urls

Published Nov 2, 2026 CVSS 4.0 · 6.3 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title Chainlit 2.12.0 SSRF via Semicolon Path Segment in MCP allowed_urls
First Time appeared Chainlit
Chainlit chainlit
Weaknesses CWE-918
CPEs cpe:2.3:a:chainlit:chainlit:2.12.0:*:*:*:*:*:*:*
Vendors & Products Chainlit
Chainlit chainlit
References
Metrics cvssV3_1

{'score': 5.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N'}

cvssV4_0

{'score': 6.3, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Nov 7, 2026, 12:22 AM
Reserved
Nov 2, 2026, 2:15 PM
Status
Deferred
Published
Nov 2, 2026, 3:17 PM
Modified
Nov 7, 2026, 1:17 AM