CVE-2026-86099

    Dashboard / Vulnerabilities / CVE-2026-86099

    CVE-2026-86099

    Published: 9 Sept 2026Last Modified: 11 Sept 2026

    Summary: Chainlit through 2.12.0 Path Traversal via socket.io sessionId

    Details: Chainlit through 2.12.0 fails to validate the client-supplied socket.io sessionId parameter, allowing unauthenticated attackers to traverse filesystem paths by injecting absolute or relative path sequences. Attackers can craft malicious sessionId values that escape the upload directory and recursively delete arbitrary directories accessible to the service process.

    References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86099.json, https://nvd.nist.gov/vuln/detail/CVE-2026-86099, https://www.vulncheck.com/advisories/chainlit-through-2.12.0-path-traversal-via-socket-io-sessionid, https://github.com/Chainlit/chainlit, https://pypi.org/project/chainlit/, https://github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/session.py, https://github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/socket.py

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 0
    Fixed -0565fd0eccb915fce159929598b053ed79f6e0c9

    Affected versions

    2.11.1
    2.11.0

    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-2026-86099 | CVE-DB