# CVE-2026-15814: Uploading a crafted image causes excessive memory allocation in the Mattermost Server

> CVE-2026-15814: Uploading a crafted image causes excessive memory allocation in the Mattermost Server. CVSS 6.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-15814
Last updated: 2026-10-07T16:02:31Z

- Published: 2026-09-14 10:39 UTC · Updated: 2026-10-07 16:02 UTC · Assigner: Mattermost
- CVSS: 6.5 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- EPSS: 0.42%, 36th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-409

## Description

Mattermost versions 11.9.x \<= 11.9.0, 11.8.x \<= 11.8.4, 11.7.x \<= 11.7.7, 10.11.x \<= 10.11.22 fail to limit the amount of memory allocated when decoding uploaded image files which allows an authenticated user to cause excessive server memory consumption and potential denial of service via uploading a specially crafted image as a profile picture, channel file attachment, team icon, or custom brand image. Mattermost Advisory ID: MMSA-2026-00719

## 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-2026-15814)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-15814)
- [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-2026-15814 · Markdown: https://rewindex.com/cve/CVE-2026-15814.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-15814 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:17:11.880Z