CVE-2026-6957
Mattermost Plugins versions <=1.1.5 fail to sanitize filenames received from federated peers before using them to construct export destination paths, which allows an administrator of a remote federated Mattermost server to write files to arbitrary locations within the target server's filestore via a malicious filename delivered through the shared-channel attachment sync protocol. Mattermost Advisory ID: MMSA-2026-00659
Published:May 27, 2026
Last Modified:Jun 2, 2026
EPS:May 27, 2026
EPSS Score:0.00056
CVSS Score:8
Affected Products
Vendor
Product
Action
Vendor
Mattermost
Product
Legal Hold
Mattermost
Legal Hold
Vendor
Mattermost
Product
Mattermost
Mattermost
Mattermost
Exploits
No exploit reference
Common Weakness Enumeration
Common Attack Pattern Enumeration and Classification (CAPEC)
References
Common Vulnerability Scoring System
Attack Vector
Network
Adjacent
Local
Physical
Privileges Required
None
Low
High
User Interaction
None
Required
Scope
Unchanged
Changed
Confidentiality
None
Low
High
Integrity
None
Low
High
Availability
None
Low
High
