High severity7.6NVD Advisory· Published Jun 12, 2026· Updated Jun 15, 2026
CVE-2026-6961
CVE-2026-6961
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
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
github.com/mattermost/mattermost-serverGo | >= 11.6.0, < 11.6.1 | 11.6.1 |
github.com/mattermost/mattermost-serverGo | >= 11.5.0, < 11.5.5 | 11.5.5 |
github.com/mattermost/mattermost-serverGo | >= 10.11.0, < 10.11.17 | 10.11.17 |
github.com/mattermost/mattermost/server/v8Go | >= 8.0.0-20250731163400-5b955468ea1e, < 8.0.0-20260423180926-c021eeaff8f0 | 8.0.0-20260423180926-c021eeaff8f0 |
Affected products
2- Range: <=11.6.1, <=11.5.4, <=10.11.15, <=10.11.16
- osv-coordsRange: < 0.0.20260827T195228-160000.1.1
Patches
Vulnerability mechanics
References
17- github.com/advisories/GHSA-8qq9-cqj8-82w4ghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-6961ghsaADVISORY
- github.com/mattermost/mattermost/commit/61d68d2d6ee81a5919597d91c736c502d7156859ghsaWEB
- github.com/mattermost/mattermost/commit/a0056ed68d95f64d7c4586985e7b7f16b96b3becghsaWEB
- github.com/mattermost/mattermost/commit/a9f3868e1eee9ec61855cd7277f39937385efffdghsaWEB
- github.com/mattermost/mattermost/commit/c021eeaff8f003034ab40f82c552cc26a710a8fdghsaWEB
- github.com/mattermost/mattermost/commit/c896a63dc44c2f9c081a0a15bfddc4e6eb50e753ghsaWEB
- github.com/mattermost/mattermost/pull/36223ghsaWEB
- github.com/mattermost/mattermost/pull/36251ghsaWEB
- github.com/mattermost/mattermost/pull/36252ghsaWEB
- github.com/mattermost/mattermost/pull/36253ghsaWEB
- github.com/mattermost/mattermost/pull/36255ghsaWEB
- github.com/mattermost/mattermost/releases/tag/v10.11.16ghsaWEB
- github.com/mattermost/mattermost/releases/tag/v11.5.5ghsaWEB
- github.com/mattermost/mattermost/releases/tag/v11.6.2ghsaWEB
- github.com/mattermost/mattermost/releases/tag/v11.7.0ghsaWEB
- mattermost.com/security-updatesnvdWEB
News mentions
1- Mattermost Discloses 7 CVEs: Privilege Escalation, Token Theft, and Federated File WriteVypr Intelligence · Jun 12, 2026