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CVE-2026-6346 — Vulnerability in...

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

Advisory Timeline

  • First published May 18, 2026 (147 days ago).
  • Last revised June 25, 2026 — 38 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

Go
Update github.com/mattermost/mattermost/server/v8 to 11.4.4 or later
go get github.com/mattermost/mattermost/server/v8@v11.4.4
Go
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
Go
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
Go
Update github.com/mattermost/mattermost/server/v8 to 11.5.2 or later
go get github.com/mattermost/mattermost/server/v8@v11.5.2
Go
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)

Affects 1 ecosystem: go (2).

PackageEcosystemAffectedFixed In
github.com/mattermost/mattermost/server/v8
go
All versions11.4.4
github.com/mattermost/mattermost/server/v8
go
All versions8.0.0-20260326202606-fac92f4a71f3
github.com/mattermost/mattermost-server
go
All versions5.3.2-0.20260326202606-fac92f4a71f3
github.com/mattermost/mattermost/server/v8
go
All versions11.5.2
github.com/mattermost/mattermost/server/v8
go
All versions10.11.14

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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