6.5Medium
Mattermost Mattermost Server
CVE-2026-14298
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 decompressed content size and enforce the configured maximum file size in the Boards archive import handler, which allows an authenticated user to cause memory exhaustion or unbounded disk consumption via a crafted .boardarchive file uploaded to the import endpoint.. Mattermost Advisory ID: MMSA-2026-00713
What this means for your business
- It affects Mattermost Server. It matters if your company, or a supplier that handles your data, runs it.
- An attacker can use it remotely, over a network, with an ordinary user login, and without anyone at your company clicking anything.
- FIRST's prediction model gives it a 0.2% chance of attack attempts being seen in the next 30 days, ranking above 15% of all known flaws.
What to do
- 1Check whether your company or your suppliers run Mattermost Server, and which version. The affected versions are listed further down this page.
- 2If you do, apply the vendor's fix. A patch or vendor advisory has been published.
Not sure if your company is exposed?
Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.
Scoring
- CVSS
- 6.5 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H- Weakness
- CWE-409
- Assigned by
- responsibledisclosure@mattermost.com
Dates
- Published
- 2026-08-13
- Last modified
- 2026-09-14
- Sources
- NVD
Affected products
- Mattermost Mattermost Server10.11.0 - 10.11.23, 11.7.0 - 11.7.8, 11.8.0 - 11.8.5, 11.9.0 - 11.9.1
As listed in the NVD configuration data. Not a statement about your estate.