Unsecured Authentication in Mattermost Affecting Jira Integration
CVE-2026-6673

6.4MEDIUM

Key Information:

Vendor

Mattermost
Status
Mattermost
Vendor
CVE Published:
22 June 2026

What is CVE-2026-6673?

Certain versions of Mattermost are vulnerable due to a failure to authenticate Atlassian Connect installed callbacks. This weakness allows remote unauthenticated attackers to inject a rogue sharedSecret during the pending-install window, potentially disrupting the integration with Jira through malicious POST requests to the /ac/installed endpoint. Users of affected Mattermost versions should implement appropriate security measures and upgrade to patch the vulnerability.

Affected Version(s)

Mattermost 11.7.0

Mattermost 11.6.0 <= 11.6.2

Mattermost 11.5.0 <= 11.5.5

References

https://mattermost.com/security-updates
vendor-advisory

CVSS V3.1

Score:
6.4
Severity:
MEDIUM
Confidentiality:
None
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
Low
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

insomnia1102
.