CVE-2026-3473
Improper file ownership validation in the Boards API allows unauthorised file access
Description
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate file ownership and access control, which allows an authenticated user to access and download files belonging to other users or teams via crafted Boards API requests using valid file IDs.. Mattermost Advisory ID: MMSA-2026-00620
No summary for this CVE yet.
CVSS Vector Breakdown
Exploitability
AV:NAttack VectorNetwork
AC:HAttack ComplexityHigh
PR:LPrivileges RequiredLow
UI:NUser InteractionNone
Scope
S:UScopeUnchanged
Impact
C:HConfidentialityHigh
I:LIntegrityLow
A:NAvailabilityNone
Weaknesses
Affected Products
Mattermost Inc
commercial·USaka mattermost
Exploitability
Official Patch Available
Attack Graph
Products CVE Techniques Tactics
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MITRE ATT&CK
1 technique Initial Access
References
https://mattermost.com/security-updates
mattermost.com
https://mattermost.com/security-updates
mattermost.com
https://feedly.com/cve/CVE-2026-3473
feedly.com
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