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CVE-2026-3471

Opening a window with {{javascript:alert()}} as URL causes crash in the Mattermost Desktop App

Published: May 18, 2026Updated: Jun 5, 2026 Sources: CVE List NVDCWE-939
NVD MITRE
6.5CVSSMEDIUM
EPSS Score
0.2%
Top 91.9%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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

CVSS Vector Breakdown

AV:NAC:LPR:NUI:RS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-939

Affected Products

MattermostMattermost
On-premWeb App
Communications / messaging-chat
mattermost desktopmattermost
On-premDesktop App
Communications / messaging-chat
mattermostcommercialUSCommunications

Exploitability

Official Patch Available

References

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

Timeline

Published
May 18, 2026
Last Updated
Jun 5, 2026

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