# CVE-2026-3471: Opening a window with {{javascript:alert()}} as URL causes crash in the Mattermost Desktop App

> CVE-2026-3471: Opening a window with {{javascript:alert()}} as URL causes crash in the Mattermost Desktop App. CVSS 6.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-3471
Last updated: 2026-06-17T10:43:38Z

- Published: 2026-05-18 08:45 UTC · Updated: 2026-06-17 10:43 UTC · Assigner: Mattermost
- CVSS: 6.5 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
- EPSS: 0.18%, 8th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-939

## 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

## Affected vendors and products

- Mattermost: Mattermost

## Tracked companies

- [Mattermost](https://rewindex.com/company/mattermost.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-3471)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-3471)
- [https://mattermost.com/security-updates](https://mattermost.com/security-updates)

---

_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


---
Canonical: https://rewindex.com/cve/CVE-2026-3471 · Markdown: https://rewindex.com/cve/CVE-2026-3471.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-3471 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:05:41.249Z