Vulnerability in Mattermost

CVE-2026-75588

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

Published · last modified .

CVSS v3 metric

CVSS v3 base score 2.6 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.002 (13.1th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 13th percentile — 13.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-75588: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-75588?
CVE-2026-75588 is a low-severity vulnerability in Mattermost, classified under CWE-1287. CVSS score: 2.6/10. Published 2026-09-17.
How severe is CVE-2026-75588?
Low severity. CVSS v3 base score is 2.6 out of 10.