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Description

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

PUBLISHED Reserved 2026-02-23 | Published 2026-03-25 | Updated 2026-03-26 | Assigner Mattermost




MEDIUM: 4.3CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Problem types

CWE-754: Improper Check for Unusual or Exceptional Conditions

Product status

Default status
unaffected

11.4.0 (semver)
affected

11.3.0 (semver)
affected

11.2.0 (semver)
affected

10.11.0 (semver)
affected

11.5.0
unaffected

11.4.1
unaffected

11.3.2
unaffected

11.2.4
unaffected

10.11.12
unaffected

Credits

mk7120 finder

References

mattermost.com/security-updates (MMSA-2026-00595) vendor-advisory

cve.org (CVE-2026-20719)

nvd.nist.gov (CVE-2026-20719)

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