CVE-2026-1046 Mattermost CVE debrief

Who should care

Mattermost Desktop App users, administrators, and security teams should verify their version and apply updates if necessary. Additionally, security teams should review compensating controls for exposed systems while remediation is scheduled and verified. Operators and platform administrators should also be aware of the vulnerability and its potential impact on the system. Vulnerability management teams should prioritize this issue due to its high severity.

Why it matters

The Mattermost Desktop App vulnerability allows a malicious Mattermost server to execute arbitrary executables on a user's system via the Help menu, affecting versions <=6.0, 6.2.0, and 5.2.13.0. Users should verify their version and apply updates if necessary.

• Potential arbitrary executable execution on user's system
• Possible malicious activity via Help menu
• Version verification and update required
• Restrict access to Help menu recommended

Technical summary

The Mattermost Desktop App fails to validate help links, allowing a malicious Mattermost server to execute arbitrary executables on a user's system via the Help menu. This issue affects versions <=6.0, 6.2.0, and 5.2.13.0. The vulnerability has a high CVSS score of 7.6 and is considered a high-risk issue. The app's failure to validate help links allows a malicious server to execute arbitrary code, which can lead to a compromise of the system. Users should verify their version and apply updates if necessary to prevent exploitation.

Defensive priority

High

Recommended defensive actions

• Verify Mattermost Desktop App version and apply updates if necessary
• Restrict access to the Help menu
• Monitor for suspicious activity
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD detail page provide information on the vulnerability, including its description, CVSS score, and affected versions. The Mattermost Advisory ID MMSA-2026-00577 also provides additional context on the vulnerability. However, the evidence is limited, and defenders should verify the affected scope and severity with the vendor. The CVE record was published on 2026-02-16T13:16:00.793Z and has not been modified since then.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.