Mattermost versions before 11.1.3, 10.11.10, and 11.2.2 incorrectly ignore permission checks while creating Jira issues, enabling an authenticated user who can access the Jira plugin to retrieve the full content and attachments of any post the user otherwise cannot see. This privilege escalation flaw stems from inadequate authorization controls (CWE‑863). The resulting leakage can expose sensitive information to unauthorized personnel or systems.

Versions of Mattermost Mattermost Server 10.11.x up to 10.11.9, 11.1.x up to 11.1.2, and 11.2.x up to 11.2.1 are impacted. Users running these releases are vulnerable to the confidentiality breach described above.

The vulnerability carries a CVSS score of 4.3, indicating moderate severity. The EPSS score is < 1%, suggesting a low probability of exploitation in the near term. It does not currently appear in the CISA KEV catalog. Exploitation requires an authenticated attacker with access to the Jira plugin, typically through legitimate plugin use or via compromised credentials. Without such access, the flaw remains unexploitable.