GCVE-110-NCSC-2026-305

Advisory PublishedCVSS 6.5/10

Vulnetix · Advisory published August 19, 2026

Mattermost versions 11.7.x through 11.7.6, 10.11.x through 10.11.21, and 11.8.x through 11.8.3 contain a vulnerability where improper validation of WebSocket command field types allows an authenticated user to crash the plugin process and cause denial of service via a crafted custom_focalboard_SUBSCRIBE_TEAM message with a non-string teamId.

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Weaknesses (CWE)

CWE-704Incorrect Type Conversion or CastCWE-863Incorrect AuthorizationCWE-862Missing AuthorizationCWE-459Incomplete Cleanup

Risk Scores

CVSS 3.1

6.5/10

Medium · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Affected Products

Vendor	Product	Versions	Platforms
Mattermost	vers:unknown/*	—	—

Aliases

CVE-2026-10080 CVE-2026-10527 CVE-2026-15754 CVE-2026-16044 CVE-2026-16045 CVE-2026-16046 CVE-2026-16047 CVE-2026-16048 CVE-2026-16049 CVE-2026-9693 CVE-2026-9816 CVE-2026-9859

References

advisory

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