Mattermost DoS via Unchecked Resource Consumption in Auth'd Users (<=11.9.0)
CVE-2026-14298 Published on August 13, 2026
Boards archive import endpoint allows resource exhaustion via zip bomb and file size limit bypass in Mattermost
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
Vulnerability Analysis
CVE-2026-14298 is exploitable with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Weakness Type
What is a Data Amplification Vulnerability?
The software does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output. An example of data amplification is a "decompression bomb," a small ZIP file that can produce a large amount of data when it is decompressed.
CVE-2026-14298 has been classified to as a Data Amplification vulnerability or weakness.
Products Associated with CVE-2026-14298
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Affected Versions
Mattermost:- Version 11.9.0, <= 11.9.0 is affected.
- Version 11.8.0, <= 11.8.4 is affected.
- Version 11.7.0, <= 11.7.7 is affected.
- Version 10.11.0, <= 10.11.22 is affected.
- Version 11.10.0 is unaffected.
- Version 11.9.1 is unaffected.
- Version 11.8.5 is unaffected.
- Version 11.7.8 is unaffected.
- Version 10.11.23 is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.