CVE-2026-6961
Mattermost doesn't sanitize FileInfo.Name received from federated peers during shared channel file sync
Summary
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 fail 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
Affected packages
| Ecosystem | Package | Affected versions | Fixed versions |
|---|---|---|---|
| Go | github.com/mattermost/mattermost-server | — | 11.6.1, 11.5.5, 10.11.17 |
| Go | github.com/mattermost/mattermost/server/v8 | — | 8.0.0-20260423180926-c021eeaff8f0 |
Remediation: Upgrade to 11.6.1 or later.
References
Includes data from the GitHub Advisory Database, licensed under CC-BY 4.0.
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EPSS scores provided by the FIRST.org Exploit Prediction Scoring System.