HIGH 7.6
GHSA-8qq9-cqj8-82w4
Mattermost doesn't sanitize FileInfo.Name received from federated peers during shared channel file sync
Quick fix
GHSA-8qq9-cqj8-82w4 — github.com/mattermost/mattermost-server: upgrade to the fixed version with the command below.
go get github.com/mattermost/mattermost-server@v11.6.1Details
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
Are you affected?
Enter the version of the package you're using.
Affected packages
Go / github.com/mattermost/mattermost-server
Introduced in:
11.6.0 Fixed in: 11.6.1 Fix
go get github.com/mattermost/mattermost-server@v11.6.1 Go / github.com/mattermost/mattermost-server
Introduced in:
11.5.0 Fixed in: 11.5.5 Fix
go get github.com/mattermost/mattermost-server@v11.5.5 Go / github.com/mattermost/mattermost-server
Introduced in:
10.11.0 Fixed in: 10.11.17 Fix
go get github.com/mattermost/mattermost-server@v10.11.17 Go / github.com/mattermost/mattermost/server/v8
Introduced in:
8.0.0-20250731163400-5b955468ea1e Fixed in: 8.0.0-20260423180926-c021eeaff8f0 Fix
go get github.com/mattermost/mattermost/server/v8@v8.0.0-20260423180926-c021eeaff8f0 References
- https://nvd.nist.gov/vuln/detail/CVE-2026-6961 [ADVISORY]
- https://github.com/mattermost/mattermost/pull/36255 [WEB]
- https://github.com/mattermost/mattermost/pull/36253 [WEB]
- https://github.com/mattermost/mattermost/pull/36252 [WEB]
- https://github.com/mattermost/mattermost/pull/36251 [WEB]
- https://github.com/mattermost/mattermost/pull/36223 [WEB]
- https://github.com/mattermost/mattermost/commit/c896a63dc44c2f9c081a0a15bfddc4e6eb50e753 [WEB]
- https://github.com/mattermost/mattermost/commit/c021eeaff8f003034ab40f82c552cc26a710a8fd [WEB]
- https://github.com/mattermost/mattermost/commit/a9f3868e1eee9ec61855cd7277f39937385efffd [WEB]
- https://github.com/mattermost/mattermost/commit/a0056ed68d95f64d7c4586985e7b7f16b96b3bec [WEB]
- https://github.com/mattermost/mattermost/commit/61d68d2d6ee81a5919597d91c736c502d7156859 [WEB]
- https://github.com/mattermost/mattermost/releases/tag/v10.11.16 [WEB]
- https://github.com/mattermost/mattermost/releases/tag/v11.5.5 [WEB]
- https://github.com/mattermost/mattermost/releases/tag/v11.6.2 [WEB]
- https://github.com/mattermost/mattermost/releases/tag/v11.7.0 [WEB]
- https://mattermost.com/security-updates [WEB]
- https://github.com/mattermost/mattermost [PACKAGE]