CVE Feed

    Dashboard / CVE / CVE-2026-6673

    CVE-2026-6673

    Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret and disrupt the Jira integration via POST to /ac/installed during the pending-install window.. Mattermost Advisory ID: MMSA-2026-00654

    Published:Jun 22, 2026
    Last Modified:Jun 22, 2026
    EPS:Jun 22, 2026
    EPSS Score:
    CVSS Score:6.4

    Affected Products

    Vendor
    Mattermost
    Product
    Mattermost

    Exploits

    No exploit reference

    Related CVEs

    CVE-2026-75587 (CVSS 3.6) — Mattermost Desktop App versions <=6.2 6.2.2.0 fail to redact the pre-auth secret when generating a diagnostics…
    CVE-2026-9693 (CVSS 3.5) — Mattermost versions 10.11.x <= 10.11.20, 11.7.x <= 11.7.5 Mattermost fails to remove thread membership records…
    CVE-2026-9859 (CVSS 6.5) — Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to enforce PermissionManageBo…
    CVE-2026-9816 (CVSS 8.3) — Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate BoardMember.Schem…
    CVE-2026-10080 (CVSS 6.5) — Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fails to validate WebSocket comman…
    CVE-2026-10527 (CVSS 6.3) — Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fails to reconcile SchemeAdmin fla…
    CVE-2026-15754 (CVSS 4.2) — Mattermost versions 11.7.x <= 11.7.6, 11.8.x <= 11.8.3 The access control policy unassign endpoint fails to re…
    CVE-2026-16044 (CVSS 5.4) — Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to prevent guest users from receiving Board Adm…
    CVE-2026-16045 (CVSS 4.3) — Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 Mattermost failed to restrict OAuth deauthorization …
    CVE-2026-16049 (CVSS 4.3) — Mattermost Plugins versions <=11.8 10.20.11 11.5.7.0 _The Mattermost GitLab plugin fails to verify channel per…

    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