Vulnerability · Published Sep 17, 2026 · Assigned by Mattermost
CVE-2026-75588Mattermost Desktop App plugin popout scheme validation bypass
Low 2.6
In plain English
A low-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 13% of all known vulnerabilities).
Severity (CVSS 3.1)2.6Low
Exploit odds (30 days)0.2%top 86.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Mattermost Desktop App versions <=6.2 6.2.2.0 fail to validate the URL scheme when checking whether a target URL is internal to the connected server, which allows a network-positioned attacker to load a plugin popout window over an insecure connection via a link using a downgraded URL scheme. Mattermost Advisory ID: MMSA-2026-00717
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mattermost | Mattermost | 0 – through 6.2.2 |
Weakness: CWE-1287 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:N
References
- MMSA-2026-00717 vendor-advisory