GHSA-vc7j-h8xg-fv5x

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    GHSA-vc7j-h8xg-fv5x

    Published: 4 Aug 2023Last Modified: 10 Sept 2026

    Summary: matrix-appservice-bridge doesn't verify the sub parameter of an openId token exhange, allowing unauthorized access to provisioning APIs

    Details: ### Impact A malicious Matrix server can use a foreign user's MXID in an OpenID exchange, allowing a bad actor to impersonate users when using the provisioning API. ### Details The library does not check that the servername part of the `sub` parameter (containing the user's *claimed* MXID) is the same as the servername we are talking to. A malicious actor could spin up a server on any given domain, respond with a `sub` parameter according to the user they want to act as and use the resulting token to perform provisioning requests. ### Workarounds Disable the provisioning API. If the bridge does not use the provisioning API, you are not vulnerable.

    References: https://github.com/matrix-org/matrix-appservice-bridge/security/advisories/GHSA-vc7j-h8xg-fv5x, https://nvd.nist.gov/vuln/detail/CVE-2023-38691, https://github.com/matrix-org/matrix-appservice-bridge/commit/4c6723a5e7beda65cdf1ae5dbb882e8beaac8552, https://github.com/matrix-org/matrix-appservice-bridge

    Affected packages

    Package

    Name: matrix-appservice-bridge

    Purl: pkg:npm/matrix-appservice-bridge

    Affected ranges

    Type: SEMVER

    Events:

    Introduced- 4.0.0
    Fixed -8.1.2

    Affected versions

    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
    GHSA-vc7j-h8xg-fv5x | CVE-DB