CVE-2026-1628

Mattermost allows external websites to open within the app, exposing preload functionality to non-trusted sites.

CVSS 4.6 MEDIUMEPSS 0.1%CWE-829

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 4.6EPSS 0.1%KEV nãoPoC —Nuclei —Metasploit —Patch referenciado

Lifecycle

02 Mar 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

Mattermost Desktop App versions <=5.13.3 fail to attach listeners restricting navigation to external sites within the Mattermost app which allows a malicious server to expose preload script functionality to untrusted servers via having a user open an external link in their Mattermost server. Mattermost Advisory ID: MMSA-2026-00596

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

Affected products

Mattermost · Mattermost

Want to know if your infrastructure is exposed to this?

Talk to TrueHacking →

References

https://mattermost.com/security-updates