CVE-2026-15814

medium

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 upload…

Vendor / product: Mattermost — mattermost server

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

CVSS

6.5

6.5 (CVSS v3.1)

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Severity source: NVD CVSS v3.1 (responsibledisclosure@mattermost.com)

Timeline (UTC)

Published: 2026-09-14 11:17

Modified: 2026-10-07 16:02

NVD status: Analyzed

Last synced 1 day ago

Verified against the source API 2026-10-27 06:52 UTC

Exploitation

Not listed in CISA KEV (as of last catalog sync)

Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

mattermost / mattermost_server ≥10.11.0 <10.11.23, ≥11.7.0 <11.7.8, ≥11.8.0 <11.8.5, ≥11.9.0 <11.9.1

Weakness classification (CWE)

CWE-409

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

Vendor advisory: https://mattermost.com/security-updates

References

https://mattermost.com/security-updates responsibledisclosure@mattermost.com

Data sources

NVD CVE API 2.0 — fetched 2026-10-27 06:52 UTC · record ↗

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CVE-2026-15814

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