PT-2026-7984 · Mattermost · Mattermost

Juho Forsén · CVE-2026-20796 · Published 2026-02-13 · Updated 2026-07-30

Positive Technologies (AI Summary)

CVSS v3.1

3.1

Low

Base vector

AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N

Name of the Vulnerable Software and Affected Versions Mattermost versions 10.11.0 through 10.11.9

Description Mattermost versions 10.11.0 through 10.11.9 do not properly validate channel membership when retrieving data, potentially allowing a deactivated user to learn team names they should not have access to. This occurs due to a race condition in the /common teams API endpoint.

Recommendations Update to a version later than 10.11.9.

Exploit

Fix

Time Of Check To Time Of Use

Weakness Enumeration

CWE-367

Related Identifiers

CVE-2026-20796

GHSA-2XF7-HMF6-P64J

GO-2026-4495

OPENSUSE-SU-2026:21483-1

SUSE-SU-2026:0757-1

Affected Products

Mattermost

References · 1752

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/20xxx/CVE-2026-20796.json · Exploit
• https://osv.dev/vulnerability/SUSE-SU-2026:0757-1 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2026-20796 · Vendor Advisory
• https://mattermost.com/security-updates · Vendor Advisory
• https://osv.dev/vulnerability/GO-2026-4495 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-2xf7-hmf6-p64j · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-20796 · Security Note
• https://osv.dev/vulnerability/openSUSE-SU-2026:21483-1 · Vendor Advisory
• https://github.com/mattermost/mattermost · Note
• https://suse.com/security/cve/CVE-2026-27589 · Note
• https://suse.com/security/cve/CVE-2025-65797 · Note
• https://suse.com/security/cve/CVE-2026-44427 · Note
• https://suse.com/security/cve/CVE-2026-7736 · Note
• https://suse.com/security/cve/CVE-2026-27137 · Note
• https://suse.com/security/cve/CVE-2026-25232 · Note