Vulnerability record/PUBLISHED/Published Oct 28, 2026 21:41:15 UTC
CVE-2026-93851
Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10 fail to validate the target post ID in the Agents plugin's mention reminder component, which allows an authenticated user who can post in a channel visible to a system administrator to cause the administrator's browser to send an unintended API request, resulting in replacement of an installed plugin and code execution on the server, via a crafted post containing a forged mention reminder that the administrator clicks. Mattermost Advisory ID: MMSA-2026-00742
Base score8.0/ 10
SeverityHighCVSS 3.1
Exploitability / impact
CVSS metric breakdown
Base severityHigh
Attack vectorNetworkAV
Attack complexityHighAC
Privileges requiredLowPR
User interactionRequiredUI
ScopeChangedS
Confidentiality impactHighC
Integrity impactHighI
Availability impactHighA
CVSS vector string
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:HCVSS communicates standardized severity and impact characteristics. It does not establish whether a system is exploitable in your specific environment.
Record context
CVE Numbering AuthorityMattermost
Last updatedOct 28, 2026 21:41:15 UTC
PublishedOct 28, 2026 21:41:15 UTC
ReservedSep 18, 2026 18:43:37 UTC
Credits
- z01dberg