Vulnerability Details 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, 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
Exploit prediction scoring system (EPSS) score
EPSS Score 0.002
EPSS Ranking 7.4%
CVSS Severity
CVSS v3 Score 6.4
References