# CVE-2026-3495: Unescaped variables during error page composition

> CVE-2026-3495: Unescaped variables during error page composition. CVSS 3.8 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-3495
Last updated: 2026-10-14T20:10:00Z

- Published: 2026-05-18 06:58 UTC · Updated: 2026-10-14 20:10 UTC · Assigner: Mattermost
- CVSS: 3.8 (CVSS 3.1) · Severity: Low · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N
- EPSS: 0.14%, 4th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-79

## Description

Mattermost versions 11.5.x \<= 11.5.1, 10.11.x \<= 10.11.13 fail to escape some variables that could contain malicious content during error page composition which allows an attacker with access to edit some site configuration to execute some malicious code via injecting some JS as part of those values.. Mattermost Advisory ID: MMSA-2026-00622

## 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-2026-3495)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-3495)
- [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-2026-3495 · Markdown: https://rewindex.com/cve/CVE-2026-3495.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-3495 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:13:40.614Z