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mattermost / mattermost_server CVEs

Beta · best-effort

452 CVEs tagged to mattermost / mattermost_server17 Critical, 63 High, 283 Medium, 89 Low, 0 Unrated.

CVE-2026-9824

Published Jul 13, 2026

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to check the manage_shared_channels permission in the /share-channel autocomplete handler, which a…

CVSS 4.3 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-9820

Published Jul 13, 2026

Mattermost versions 11.7.x <= 11.7.2, 10.11.x <= 10.11.19 fail to sanitize team objects returned by the scheme teams endpoint, which allows a user with the User Manager role to ob…

CVSS 3.8 · Low
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-6541

Published Jul 13, 2026

Mattermost versions 11.7.x <= 11.7.1, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to restrict metric configuration changes to the playbook being saved, which allows an authenticate…

CVSS 4.3 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-9708

Published Jul 13, 2026

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to validate that an assigned incoming webhook user has access to the target team or channel, which…

CVSS 4.9 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-9597

Published Jul 13, 2026

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4 fail to verify whether a guest account is deactivated before creating a session in the magic-link token login path, which al…

CVSS 5.4 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-9571

Published Jul 13, 2026

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to invalidate OAuth refresh tokens upon user account deactivation, which allows a deactivated user…

CVSS 5.9 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-6850

Published Jul 13, 2026

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to validate the length and content of message attachment field values, which allows an authenticat…

CVSS 6.5 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-10106

Published Jul 13, 2026

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to verify that the channel referenced in an action cookie matches the channel of the target post,…

CVSS 6.5 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-10103

Published Jul 13, 2026

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to verify post ownership in the shared channel inbound sync handler, which allows an authenticated…

CVSS 4.3 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-10085

Published Jul 13, 2026

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to restrict the group_constrained channel flag to public and private channels that support group s…

CVSS 5.4 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-4339

Published Jun 26, 2026

Mattermost versions 10.11.x <= 10.11.18, 11.6.x <= 11.6.3, 11.5.x <= 11.5.6 fail to validate attachment URLs against internal or private IP ranges in the Mattermost Agents plugin…

CVSS 6.5 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-3472

Published Jun 26, 2026

Mattermost versions 10.11.x <= 10.11.18, 11.6.x <= 11.6.3, 11.5.x <= 11.5.6 fail to properly apply markdown image rendering restrictions to AI bot tool result posts, which allows…

CVSS 3.5 · Low
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-8823

Published Jun 22, 2026

Mattermost versions 11.7.x <= 11.7.0, 10.11.x <= 10.11.17 fail to validate bot targets when demoting users to guests which allows a lower-privileged administrator to degrade arbit…

CVSS 3.8 · Low
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-9162

Published Jun 22, 2026

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 invalidate cached authentication state for active WebSocket connections durin…

CVSS 4.3 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-8074

Published Jun 22, 2026

Mattermost versions 11.7.x <= 11.7.0, 10.11.x <= 10.11.17 fail to enforce bot-specific permission checks on the user active status endpoint, which allows a User Manager with user…

CVSS 3.8 · Low
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-6673

Published Jun 22, 2026

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 unauthe…

CVSS 6.4 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-6062

Published Jun 22, 2026

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 validate channel ownership of an existing subscription before applying edits…

CVSS 6.4 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-5139

Published Jun 22, 2026

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 enforce administrator authorization on the {{setDefaultInstance}} call within…

CVSS 5.4 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-7387

Published Jun 12, 2026

Mattermost 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 Mattermost fails to require role-management authorization when setting the scheme_…

CVSS 8.8 · High
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-7184

Published Jun 12, 2026

Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15 fail to sanitize the Remote Cluster API response on PATCH operations, which allows authenticated users…

CVSS 6.5 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-6961

Published Jun 12, 2026

Mattermost 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 Mattermost fails to sanitize FileInfo.Name received from federated peers during sh…

CVSS 7.6 · High
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-6739

Published Jun 12, 2026

Mattermost 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 system-level permission when patching protected default system rol…

CVSS 6.7 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-6689

Published Jun 12, 2026

Mattermost 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 enforce PermissionInviteUser when setting AllowOpenInvite or AllowedDomain…

CVSS 4.3 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-6046

Published Jun 12, 2026

Mattermost 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 validate that a username returned during bot registration belongs to a bot…

CVSS 5.3 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-3433

Published Jun 12, 2026

Mattermost 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 restrict role_updated websocket event broadcasts to members of the affecte…

CVSS 4.3 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort
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