CVE-2026-6673

published 2026-06-22

CVE-2026-6673: 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…

Priority P3 37 medium 6.4 CVSS 3.1

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

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 unauthenticated attacker to inject a rogue sharedSecret and disrupt the Jira integration via POST to /ac/installed during the pending-install window.. Mattermost Advisory ID: MMSA-2026-00654

Affected

8 ranges

Vendor	Product	Version range	Fixed in
mattermost	mattermost	10.11.0 – 10.11.17	—
mattermost	mattermost	11.5.0 – 11.5.5	—
mattermost	mattermost	11.6.0 – 11.6.2	—
mattermost	mattermost	11.7.0 – 11.7.0	—
mattermost	mattermost_server	>= 10.11.0 < 10.11.18	10.11.18
mattermost	mattermost_server	>= 11.5.0 < 11.5.6	11.5.6
mattermost	mattermost_server	>= 11.6.0 < 11.6.3	11.6.3
mattermost	mattermost_server	>= 11.7.0 < 11.7.1	11.7.1

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CWE-306