CVE-2026-6673
Mattermost Jira plugin had unauthenticated {{/ac/installed}} lifecycle callback during pending Jira Cloud install
CVSS Score
6.4
EPSS Score
0.0%
EPSS Percentile
0th
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
| CWE | CWE-306 |
| Vendor | mattermost |
| Product | mattermost |
| Published | Jun 22, 2026 |
| Last Updated | Jun 22, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:H Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High
Affected Versions
Mattermost / Mattermost
11.7.0 ≤ 11.7.0 11.6.0 ≤ 11.6.2 11.5.0 ≤ 11.5.5 10.11.0 ≤ 10.11.17
Credits
insomnia1102