Mattermost Boards Plugin DoS via non-Object fields.properties (11.9.0)
CVE-2026-13417 Published on September 14, 2026
Boards plugin denial of service via unvalidated block fields.properties
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 validate the type of `fields.properties` on block creation which allows an authenticated user with editor access to a board to crash the Boards plugin worker and trigger a denial of service via a child block whose `fields.properties` is a non-object value. Mattermost Advisory ID: MMSA-2026-00710
Vulnerability Analysis
CVE-2026-13417 can be exploited 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 small impact on availability.
Weakness Type
Improper Check for Unusual or Exceptional Conditions
The software does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the software.
Products Associated with CVE-2026-13417
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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.