# CVE-2026-1628: Mattermost allows external websites to open within the app, exposing preload functionality to non-trusted sites.

> CVE-2026-1628: Mattermost allows external websites to open within the app, exposing preload functionality to non-trusted sites.. CVSS 4.6 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-1628
Last updated: 2026-06-17T10:16:13Z

- Published: 2026-03-02 13:24 UTC · Updated: 2026-06-17 10:16 UTC · Assigner: Mattermost
- CVSS: 4.6 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
- EPSS: 0.14%, 4th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-829

## Description

Mattermost Desktop App versions \<=5.13.3 fail to attach listeners restricting navigation to external sites within the Mattermost app which allows a malicious server to expose preload script functionality to untrusted servers via having a user open an external link in their Mattermost server. Mattermost Advisory ID: MMSA-2026-00596

## 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-2026-1628)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-1628)
- [https://mattermost.com/security-updates](https://mattermost.com/security-updates)

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_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/)_


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Canonical: https://rewindex.com/cve/CVE-2026-1628 · Markdown: https://rewindex.com/cve/CVE-2026-1628.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-1628 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:10:48.200Z