CVE-2025-64641: Mattermost Jira plugin crafted action leaks Jira issue details

Severity: medium (CVSS 4.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-12-24 · updated 2026-10-19
Weakness: CWE-863

Description

Mattermost versions 11.1.x <= 11.1.0, 11.0.x <= 11.0.5, 10.12.x <= 10.12.3, 10.11.x <= 10.11.7 fail to verify that post actions invoking /share-issue-publicly were created by the Jira plugin which allowed a malicious Mattermost user to exfiltrate Jira tickets when victim users interacted with affected posts

Affected products

Mattermost: from 10.11.0 before 10.11.8; from 10.12.0 before 10.12.4; from 11.0.0 before 11.0.6; from 11.1.0 before 11.1.1 — fixed in 10.11.8, 10.12.4, 11.0.6, 11.1.1

How to fix

Upgrade to a fixed version: Mattermost 10.11.8, 10.12.4, 11.0.6, 11.1.1. Check the vendor advisory for mitigations.

References

https://mattermost.com/security-updates

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