CVE-2026-6673
CWE-306Published: June 22, 2026· Updated: Jun 23, 2026
Official Description
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
Technical Analysis
CVE-2026-6673 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
A successful exploit results in full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 6.4.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
Official Patches & Advisories
All References (1)
Quick Facts
Related CVEs (CWE-306)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2026-6673 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts