Mattermost Jira Plugin Vulnerability Allowing Ticket Exfiltration

A vulnerability exists in Mattermost versions 11.1.x through 11.1.0, 11.0.x through 11.0.5, 10.12.x through 10.12.3, and 10.11.x through 10.11.7. The issue arises because these versions do not properly verify that post actions invoking '/share-issue-publicly' were generated by the Jira plugin. This oversight enabled a malicious Mattermost user to exfiltrate Jira tickets by manipulating posts that victim users interacted with.

Impact

Exploitation of this vulnerability allowed for the unauthorized exfiltration of Jira tickets from Mattermost users.

Remediation

Users can upgrade to Mattermost versions 11.2.0, 11.1.0, 11.0.6, or 10.12.4 to address this vulnerability.