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Description

Mattermost Desktop App versions <=6.1 6.0.1 5.4.13.0 fail to prevent an invalid URL from loading in a pop-up window in the Mattermost Desktop App which allows a malicious server owner to repeated crash the application via calling {{window.open('javascript:alert()');}}. Mattermost Advisory ID: MMSA-2026-00618

PUBLISHED Reserved 2026-03-03 | Published 2026-05-18 | Updated 2026-05-18 | Assigner Mattermost




MEDIUM: 6.5CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Problem types

CWE-939: Improper Authorization in Handler for Custom URL Scheme

Product status

Default status
unaffected

Any version
affected

Any version
affected

6.2.0
unaffected

6.1.1.0
unaffected

5.13.5.0
unaffected

Credits

game0v3r finder

References

mattermost.com/security-updates (MMSA-2026-00618) vendor-advisory

cve.org (CVE-2026-3471)

nvd.nist.gov (CVE-2026-3471)

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