GitHub Advisoryadvisory · Go
GHSA-jqgv-39mg-7c2r Mattermost doesn't authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret
MEDIUM
Official page ↗
- Aliases
- CVE-2026-6673
- Ecosystem
- Go
- Packages
- github.com/mattermost/mattermost-server
- Severity
- Moderate
- CVSS vector
- CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:H
- Weaknesses
- CWE-306
- Reviewed
- 2026-09-15
Affected packages
• Go github.com/mattermost/mattermost-server: >= 11.7.0, < 11.7.1 → fixed in 11.7.1
• Go github.com/mattermost/mattermost-server: >= 11.6.0, < 11.6.3 → fixed in 11.6.3
• Go github.com/mattermost/mattermost-server: >= 11.5.0, < 11.5.6 → fixed in 11.5.6
• Go github.com/mattermost/mattermost-server: >= 10.11.0, < 10.11.18 → fixed in 10.11.18
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
Related
Alias · CVE (1)
- 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… vulnerability
Weakness · CWE (1)
- CWE-306 Missing Authentication for Critical Functionality weakness