{"id":"CVE-2026-7387","aliases":["GHSA-6hxm-w4hv-vgvw"],"title":"Mattermost doesn't require role-management authorization when setting the scheme_admin flag on group syncable link and patch endpoints","summary":"Mattermost doesn't require role-management authorization when setting the scheme_admin flag on group syncable link and patch endpoints","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","vendor":"mattermost","product":"github.com/mattermost/mattermost-server","ecosystem":"go","affected":["github.com/mattermost/mattermost-server >= 11.6.0, < 11.6.1","github.com/mattermost/mattermost-server >= 11.5.0, < 11.5.5","github.com/mattermost/mattermost-server >= 10.11.0, < 10.11.17","github.com/mattermost/mattermost/server/v8 >= 8.0.0-20250731163400-5b955468ea1e, < 8.0.0-20260506065351-202d125afa87"],"patched":["github.com/mattermost/mattermost-server 11.6.1","github.com/mattermost/mattermost-server 11.5.5","github.com/mattermost/mattermost-server 10.11.17","github.com/mattermost/mattermost/server/v8 8.0.0-20260506065351-202d125afa87"],"published":"2026-06-12","updated":"2026-08-25","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-6hxm-w4hv-vgvw","references":[{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-7387"},{"url":"https://github.com/mattermost/mattermost/pull/36434"},{"url":"https://github.com/mattermost/mattermost/pull/36432"},{"url":"https://github.com/mattermost/mattermost/pull/36431"},{"url":"https://github.com/mattermost/mattermost/pull/36423"},{"url":"https://github.com/mattermost/mattermost/pull/36316"},{"url":"https://github.com/mattermost/mattermost/commit/d5f29c8ebbeb04460d16d9e2635ce50deeb78428"},{"url":"https://github.com/mattermost/mattermost/commit/a9e574a82633915f22071f0d7ca2b006f249ec2a"},{"url":"https://github.com/mattermost/mattermost/commit/8c72083414e675c97987374395e36d1f36b4bd8a"},{"url":"https://github.com/mattermost/mattermost/commit/202d125afa87fe39611686850fd82590c99ca344"},{"url":"https://github.com/mattermost/mattermost/commit/1ce2484a00c9821ee19708d2c46720e4855033a9"},{"url":"https://github.com/mattermost/mattermost/releases/tag/v10.11.16"},{"url":"https://github.com/mattermost/mattermost/releases/tag/v11.5.5"},{"url":"https://github.com/mattermost/mattermost/releases/tag/v11.6.2"},{"url":"https://github.com/mattermost/mattermost/releases/tag/v11.7.0"},{"url":"https://mattermost.com/security-updates"},{"url":"https://github.com/mattermost/mattermost"}],"tags":["osv","go"],"epss":0.0031,"epssPercentile":0.24028,"ingestedAt":"2026-08-25T19:26:22.895Z","slug":"CVE-2026-7387","body":"## Overview\n\nMattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to require role-management authorization when setting the scheme_admin flag on group syncable link and patch endpoints, which allows a user with group-link permissions to escalate themselves and group members to team or channel admin via crafted API requests. Mattermost Advisory ID: MMSA-2026-00665\n\n## Affected packages\n\n- `github.com/mattermost/mattermost-server >= 11.6.0, < 11.6.1`\n- `github.com/mattermost/mattermost-server >= 11.5.0, < 11.5.5`\n- `github.com/mattermost/mattermost-server >= 10.11.0, < 10.11.17`\n- `github.com/mattermost/mattermost/server/v8 >= 8.0.0-20250731163400-5b955468ea1e, < 8.0.0-20260506065351-202d125afa87`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `github.com/mattermost/mattermost-server 11.6.1`\n- `github.com/mattermost/mattermost-server 11.5.5`\n- `github.com/mattermost/mattermost-server 10.11.17`\n- `github.com/mattermost/mattermost/server/v8 8.0.0-20260506065351-202d125afa87`","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}