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HIGH · 7.6

CVE-2026-6961

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 syn...

Vulnerability 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

CVSS Score

7.6

HIGH

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:L
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
HIGH
User Interaction
NONE
Scope
CHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
LOW

Affected Products

VendorProductVersions
MattermostMattermost Server>= 10.11.0, < 10.11.17

Related Weaknesses (CWE)

CWE-22

References

FAQ

What is CVE-2026-6961?

CVE-2026-6961 is a vulnerability with a CVSS score of 7.6 (HIGH). 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 syn...

How severe is CVE-2026-6961?

CVE-2026-6961 has been rated HIGH with a CVSS base score of 7.6/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-6961?

Check the references section above for vendor advisories and patch information. Affected products include: Mattermost Mattermost Server.