Mattermost Desktop App <=5.13.3: External Navigation Leak Exposes Preload Scripts
CVE-2026-1628 Published on March 2, 2026
Mattermost allows external websites to open within the app, exposing preload functionality to non-trusted sites.
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
Vulnerability Analysis
CVE-2026-1628 is exploitable with network access, requires user interaction and a small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.
Weakness Type
Inclusion of Functionality from Untrusted Control Sphere
The software imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere.
Products Associated with CVE-2026-1628
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Affected Versions
Mattermost:- Before and including 5.13.3 is affected.
- Version 5.13.4.0 is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.