CVE-2026-20719

low-risk

Published 2026-03-25

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 creating an issue or PR on GitHub.. Mattermost Advisory ID: MMSA-2026-00595

Do I need to act?

0.05% chance of exploitation

EPSS score — low exploit probability

Not on CISA KEV list

No confirmed active exploitation reported to CISA

Patch status unknown

Check vendor advisories for fix availability and mitigation guidance

CVSS 4.3/10 Medium

NETWORK / LOW complexity

Affected Products (1)

Mattermost Server

Affected Vendors

Mattermost

References (1)

Vendor Advisory https://mattermost.com/security-updates

/ 100

low-risk

Severity 18/34 · Moderate

Exploitability 0/34 · Minimal

Exposure 5/34 · Minimal