Vulnerability · Published Mar 2, 2026 · Assigned by Mattermost
CVE-2026-1628Mattermost allows external websites to open within the app, exposing preload functionality to non-trusted sites.
Medium 4.6
In plain English
A medium-severity security flaw in Mattermost from Mattermost. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 5% of all known vulnerabilities).
Severity (CVSS 3.1)4.6Medium
Exploit odds (30 days)0.2%top 94.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
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
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mattermost | Mattermost | 0 – through 5.13.3 |
Weakness: CWE-829 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
References
- MMSA-2026-00596 vendor-advisory