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TI-2026-02990 Aliases CVE-2026-3471GHSA-fhqj-97rr-gvhp

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

Priority LOW 28CWE-939Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

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

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00184 8th percentileScored 2026-11-07
Fix Fixed Mattermost (Mattermost): 6.2.0, 6.1.1.0, 5.13.5.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
MattermostMattermostup to 6.0.1; up to 5.4.136.2.0, 6.1.1.0, 5.13.5.0Patch availableCNA
  • Mattermost VendorMattermost Affected up to 6.0.1; up to 5.4.13 Fixed in 6.2.0, 6.1.1.0, 5.13.5.0 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:mattermost:mattermost_desktop:*:*:*:*:*:*:*:*up to 5.4.13.0; 6.0.0 – 6.0.1; 6.1.0 to before 6.2.0VulnerableMattermost
  • cpe:2.3:a:mattermost:mattermost_desktop:*:*:*:*:*:*:*:* Versions up to 5.4.13.0; 6.0.0 – 6.0.1; 6.1.0 to before 6.2.0 Vulnerable ·Mattermost

Remediation

  • Fix · CNA Mattermost (Mattermost) Fixed in 6.2.0, 6.1.1.0, 5.13.5.0

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-3471
  2. 2026-10-03 Alias added: GHSA-fhqj-97rr-gvhp

References

Advisory 1

  • TI-2019-15074 An issue was discovered in Mattermost Desktop App before 4.3.0 on macOS. CVSS 3.1CRITICAL 9.8
  • TI-2016-09099 An issue was discovered in Mattermost Desktop App before 3.4.0. CVSS 3.1CRITICAL 9.8
  • TI-2019-15079 An issue was discovered in Mattermost Desktop App before 4.2.2. CVSS 3.1HIGH 8.8
  • TI-2024-26542 RCE in desktop app in Windows by local attacker CVSS 3.1HIGH 7.8
  • TI-2026-05712 Mattermost Desktop App fails to restrict the allow list of domains which NTLM credentials are passed CVSS 3.1HIGH 7.7
  • TI-2026-00781 Arbitrary application execution via unvalidated server-controlled URLs in Help menu CVSS 3.1HIGH 7.6
See all 33 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences