CVE-2026-6961
HighCVSS 7.6Exploitation Probability (EPSS)
Low risk21th percentile - higher than 21% of all known CVEs
Summary
Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, and 10.11.x <= 10.11.16 have a vulnerability that allows improper processing of the FileInfo.Name received from federated peers. An attacker controlling a federated server can exploit this vulnerability to write files to arbitrary locations within the target server's filestore via path traversal sequences in the filename field.
Risk Assessment
This vulnerability poses a serious security risk, allowing attackers to manipulate data on the server, potentially leading to loss of confidentiality and data integrity.
Recommendation
It is recommended to update Mattermost to the latest version to mitigate this vulnerability and implement additional security measures such as monitoring and restricting access to federated servers.
Original NVD description (English source)
Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 Mattermost fails to sanitize FileInfo.Name received from federated peers during shared channel file sync, which allows an attacker who controls a federated server to write files to arbitrary locations within the target server's filestore via path traversal sequences in the filename field.. Mattermost Advisory ID: MMSA-2026-00661