CVE-2026-6346

HIGH

Mattermost doesn't sanitize sensitive configuration fields before including them in support packet generation

Published May 18, 2026Updated June 25, 2026Source: osv

Summary

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to sanitize sensitive configuration fields before including them in support packet generation, which allows a Mattermost System Admin or any party with access to a support packet to obtain sensitive credentials in plaintext via downloading a support packet from the System Console.. Mattermost Advisory ID: MMSA-2026-00607

Remediation

Upgrade to the fixed version using your package manager.

Update github.com/mattermost/mattermost/server/v8 to 11.4.4 or later

go get github.com/mattermost/mattermost/server/v8@v11.4.4

Update github.com/mattermost/mattermost/server/v8 to 8.0.0-20260326202606-fac92f4a71f3 or later

go get github.com/mattermost/mattermost/server/v8@v8.0.0-20260326202606-fac92f4a71f3

Update github.com/mattermost/mattermost-server to 5.3.2-0.20260326202606-fac92f4a71f3 or later

go get github.com/mattermost/mattermost-server@v5.3.2-0.20260326202606-fac92f4a71f3

Update github.com/mattermost/mattermost/server/v8 to 11.5.2 or later

go get github.com/mattermost/mattermost/server/v8@v11.5.2

Update github.com/mattermost/mattermost/server/v8 to 10.11.14 or later

go get github.com/mattermost/mattermost/server/v8@v10.11.14

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (5)

Package	Ecosystem	Affected	Fixed In
github.com/mattermost/mattermost/server/v8	go	All versions	11.4.4
github.com/mattermost/mattermost/server/v8	go	All versions	8.0.0-20260326202606-fac92f4a71f3
github.com/mattermost/mattermost-server	go	All versions	5.3.2-0.20260326202606-fac92f4a71f3
github.com/mattermost/mattermost/server/v8	go	All versions	11.5.2
github.com/mattermost/mattermost/server/v8	go	All versions	10.11.14

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

CWE-200
Information ExposureMITRE

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 8.7 score means for each attack dimension.

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

None

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N

References

Frequently Asked Questions

What is CVE-2026-6346?: Mattermost doesn't sanitize sensitive configuration fields before including them in support packet generation This vulnerability has been assigned a severity rating of HIGH (CVSS score: 8.7/10).
How do I check if my project is affected by CVE-2026-6346?: CVE-2026-6346 affects github.com/mattermost/mattermost/server/v8 and github.com/mattermost/mattermost-server. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-6346 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score

8.7

High exploitability or significant impact. Prioritize remediation within days.

Also Known As

GHSA-9p64-jpc7-m2rp

GO-2026-5293

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