CVE-2023-39953

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    CVE-2023-39953

    Published: 10 Aug 2023Last Modified: 12 Aug 2026

    Summary: Issuer not verified from obtained token in user_oidc

    Details: user_oidc provides the OIDC connect user backend for Nextcloud, an open-source cloud platform. Starting in version 1.0.0 and prior to version 1.3.3, missing verification of the issuer would have allowed an attacker to perform a man-in-the-middle attack returning corrupted or known token they also have access to. user_oidc 1.3.3 contains a patch. No known workarounds are available.

    References: https://hackerone.com/reports/2021684, https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/39xxx/CVE-2023-39953.json, https://github.com/nextcloud/security-advisories/security/advisories/GHSA-xx3h-v363-q36j, https://nvd.nist.gov/vuln/detail/CVE-2023-39953, https://github.com/nextcloud/user_oidc/pull/642

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 2b27bd81899d8607f82ad41c2831bef91db835a5
    Fixed -3ff24f81b96792d96a2647d7b1f857b891c84643

    Affected versions

    v1.2.0
    v1.2.1

    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-2023-39953 | CVE-DB