CVE-2026-3471 json
Opening a window with {{javascript:alert()}} as URL causes crash in the Mattermost Desktop App
published 5mo ago modified 4mo ago also EUVD-2026-30757
- cvss
- 6.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 8%
- public exploits
- 0
- none known
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
Patch / fix
- Mattermost Mattermost 5.13.5.0, 6.1.1.0, 6.2.0
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Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 5mo ago
Exploit prediction
0.18% chance of exploitation in the next 30 days, higher than 8% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H |
Affected products
- Mattermost Mattermost
Classification
- Weakness
-
- CWE-939 Improper Authorization in Handler for Custom URL Scheme
References
-
mattermost.com
/security-updates
vendor-advisory
Sources
- CVE List CVE-2026-3471
- NVD CVE-2026-3471
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