CVE-2026-120492

    Dashboard / Vulnerabilities / CVE-2026-120492

    CVE-2026-120492

    Published: 2 Nov 2026Last Modified: 8 Nov 2026

    Summary: Chainlit 2.12.0 SSRF via Semicolon Path Segment in MCP allowed_urls

    Details: 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.

    References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/120xxx/CVE-2026-120492.json, https://github.com/Chainlit/chainlit/security/advisories/GHSA-hvfh-5mj3-5f3j, https://nvd.nist.gov/vuln/detail/CVE-2026-120492, https://www.vulncheck.com/advisories/chainlit-2.12.0-ssrf-via-semicolon-path-segment-in-mcp-allowed-urls, https://github.com/Chainlit/chainlit, https://github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/mcp.py#L199-L208, https://github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/mcp.py#L90-L177

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 0565fd0eccb915fce159929598b053ed79f6e0c9
    Fixed -None

    Affected versions

    2.12.0

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    CVE-2026-120492 | CVE-DB