CVE-2026-9812

MEDIUMCVSS 6.5/10EPSS 0.37%

Last modified

CVE-2026-9812 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. 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 that a property field belongs to the specified run before updating its value which allows an authenticated user with run property-management access to crash the Playbooks plugin via a REST request referencing a property field that belongs to a different run. Mattermost Advisory ID: MMSA-2026-00684. EPSS estimates a 0.37% chance of exploitation in the next 30 days.

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 validate that a property field belongs to the specified run before updating its value which allows an authenticated user with run property-management access to crash the Playbooks plugin via a REST request referencing a property field that belongs to a different run. Mattermost Advisory ID: MMSA-2026-00684

Metrics

EPSS Probability
0.37%

28.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
MattermostMattermost Server>= 10.11.0, < 10.11.23
MattermostMattermost Server>= 11.7.0, < 11.7.8
MattermostMattermost Server>= 11.8.0, < 11.8.5
MattermostMattermost Server>= 11.9.0, < 11.9.1

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-9812?
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 that a property field belongs to the specified run before updating its value which allows an authenticated user with run property-management access to crash the Playbooks plugin via a REST request referencing a property field that belongs to a different run. Mattermost Advisory ID: MMSA-2026-00684
How severe is CVE-2026-9812?
CVE-2026-9812 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.37% probability of exploitation in the next 30 days.
How do I fix CVE-2026-9812?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST