CVE-2026-6961

CVE-2026-6961: Path traversal via unsanitized FileInfo.Name in Mattermost federation sync

Published Jun 12, 2026 CVSS 3.1 · 7.6 High EPSS < 1% KEV · Not listed
Description
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

Remediation

Vendor Solution

Update Mattermost to versions 11.7.0, 11.6.2, 11.5.5, 10.11.16, 10.11.17 or higher.

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-8qq9-cqj8-82w4 Mattermost doesn't sanitize FileInfo.Name received from federated peers during shared channel file sync
References
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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
Title CVE-2026-6961: Path traversal via unsanitized FileInfo.Name in Mattermost federation sync
Weaknesses CWE-22
References
Metrics cvssV3_1

{'score': 7.6, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Mattermost
Published
Updated
Jun 16, 2026, 1:17 PM
Reserved
Apr 24, 2026, 3:22 PM
Status
Analyzed
Published
Jun 12, 2026, 5:16 PM
Modified
Jun 18, 2026, 2:40 PM