CVSS 3.1
6.4 mediumCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:HCVE-2026-6673
Medium (6.4) in mattermost mattermost server. EPSS 0.3% chance of exploitation in the next 30 days. Fixed in github.com/mattermost/mattermost-server 10.11.18, 10.11.18+incompatible, 11.5.6.
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
Severity
- EPSS
- 0.3% chance of exploitation in the next 30 days; higher than 22% of CVEs (scores of 2026-10-31)
- CWE
- CWE-306
- Published
- Modified
- Record from
- the NVD, synced
Affected
- mattermost:mattermost_server
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-jqgv-39mg-7c2r | Go | github.com/mattermost/mattermost-server | >=11.7.0 <11.7.1 | 11.7.1 |
| GHSA-jqgv-39mg-7c2r | Go | github.com/mattermost/mattermost-server | >=11.6.0 <11.6.3 | 11.6.3 |
| GHSA-jqgv-39mg-7c2r | Go | github.com/mattermost/mattermost-server | >=11.5.0 <11.5.6 | 11.5.6 |
| GHSA-jqgv-39mg-7c2r | Go | github.com/mattermost/mattermost-server | >=10.11.0 <10.11.18 | 10.11.18 |
| GO-2026-6483 | Go | github.com/mattermost/mattermost-server | >=10.11.0+incompatible <10.11.18+incompatible >=11.5.0+incompatible <11.5.6+incompatible >=11.6.0+incompatible <11.6.3+incompatible >=11.7.0+incompatible <11.7.1+incompatible | 10.11.18+incompatible, 11.5.6+incompatible, 11.6.3+incompatible, 11.7.1+incompatible |