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Vendor archive

mattermost CVEs

Beta · best-effort

610 CVEs tagged to vendor mattermost21 Critical, 89 High, 374 Medium, 126 Low, 0 Unrated.

CVE-2026-7521

Published Jul 28, 2026

Mattermost versions 11.8.x <= 11.8.0, 11.7.x <= 11.7.3, 11.6.x <= 11.6.5, 10.11.x <= 10.11.20 fail to verify file deletion path which allows an admin with SAML system-console writ…

CVSS 5.5 · Medium
evidence mentions
1
Buzz score
11.9
Vendor/product tagsBeta · best-effort

CVE-2026-10819

Published Jul 27, 2026

Mattermost versions 11.6.x <= 11.6.5, 10.11.x <= 10.11.20, 11.8.x <= 11.8.1, 11.7.x <= 11.7.4 fail to limit the number of frames and enforce the file size cap on animated GIF uplo…

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

CVE-2026-10600

Published Jul 27, 2026

Mattermost versions 11.8.x <= 11.8.0, 11.7.x <= 11.7.3, 11.6.x <= 11.6.5, 10.11.x <= 10.11.20 fail to bound the time and resource consumption of server-side document content extra…

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

CVE-2026-9602

Published Jul 17, 2026

Mattermost Desktop App versions <=6.2 6.0.2 5.6.13.0 fail to validate payloads sent from the Mattermost Web App to the Desktop App which allows a malicious server owner to crash t…

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

CVE-2026-8075

Published Jul 17, 2026

Mattermost Desktop App versions <=6.2 5.5.13 6.0.2.0 fail to properly null check when checking for headers in the Mattermost Desktop App which allows any user to crash another cha…

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

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-2026-2299

Published Jun 25, 2026

The Mattermost Google Drive plugin before version 1.1.0 fails to validate channel membership in the file creation endpoint, allowing authenticated users with a connected Google ac…

CVSS 4.2 · Medium
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-2026-8683

Published Jun 15, 2026

Mattermost Desktop App versions <=6.1 5.5.13.0 fail to account for attempting to open extremely long URLs in the Mattermost Desktop App which allows a malicious server owner to cr…

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