What is CVE-2026-20719?

CVE-2026-20719 is a medium-severity vulnerability in Mattermost, classified under Improper Check for Unusual or Exceptional Conditions. CVSS score: 4.3/10. Published 2026-03-25.

How severe is CVE-2026-20719?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Vulnerability in Mattermost

CVE-2026-20719

Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to prevent rendering of external SVGs on link embeds which allows unauthenticated users to crash the Mattermost webapp and desktop app via c…

EPSS: 0.001 (21.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.

Affected products

Mattermost — versions 11.4.0, 11.3.0, 11.2.0

Weakness classification (CWE)

CWE-754 — Improper Check for Unusual or Exceptional Conditions

References

MMSA-2026-00595 (vendor-advisory)

Frequently asked questions

What is CVE-2026-20719?: CVE-2026-20719 is a medium-severity vulnerability in Mattermost, classified under Improper Check for Unusual or Exceptional Conditions. CVSS score: 4.3/10. Published 2026-03-25.
How severe is CVE-2026-20719?: Medium severity. CVSS v3 base score is 4.3 out of 10.