CVE-2026-81906

    Dashboard / Vulnerabilities / CVE-2026-81906

    CVE-2026-81906

    Published: 10 Sept 2026Last Modified: 12 Sept 2026

    Summary: [UNREVIEWED] OAuth Callback Login Bypasses Deactivated-Account Checks

    Details: Concrete CMS OAuth callback login path prior to version 9.5.3 did not check whether an account was active or email-validated before establishing a session. A deactivated or unvalidated user with an existing OAuth binding could complete authentication and receive a session that was fully authenticated for the callback response, with the login recorded and login events dispatched. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.

    References: https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/81xxx/CVE-2026-81906.json, https://nvd.nist.gov/vuln/detail/CVE-2026-81906, https://github.com/concretecms/concretecms

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 0
    Fixed -None

    Affected versions

    9.5.2
    9.5.1
    9.5.0
    9.5.0RC2
    9.5.0RC1

    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-2026-81906 | CVE-DB