CVE-2026-6347 — Vulnerability in...

HIGH

Mattermost doesn't sanitize sensitive configuration fields in the Mattermost Calls plugin

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 in the Mattermost Calls plugin which allows an attacker with access to a support packet to obtain TURN server credentials via the plaintext values present in the exported plugin configuration.. Mattermost Advisory ID: MMSA-2026-00605

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.

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

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

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

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

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

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

Update github.com/mattermost/mattermost-plugin-calls to 1.12.0-rc2 or later

go get github.com/mattermost/mattermost-plugin-calls@v1.12.0-rc2

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

Affected Packages (4)

Affects 1 ecosystem: go (2).

Package	Ecosystem	Affected	Fixed In
github.com/mattermost/mattermost-server	go	All versions	11.5.2
github.com/mattermost/mattermost-server	go	All versions	11.4.4
github.com/mattermost/mattermost-server	go	All versions	10.11.14
github.com/mattermost/mattermost-plugin-calls	go	All versions	1.12.0-rc2

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) 7.6 score means for each attack dimension.

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

None

Availability

Low

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

References

Frequently Asked Questions

What is CVE-2026-6347?: Mattermost doesn't sanitize sensitive configuration fields in the Mattermost Calls plugin This vulnerability has been assigned a severity rating of HIGH (CVSS score: 7.6/10).
How do I check if my project is affected by CVE-2026-6347?: CVE-2026-6347 affects github.com/mattermost/mattermost-server and github.com/mattermost/mattermost-plugin-calls. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-6347 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score

7.6

High exploitability or significant impact. Prioritize remediation within days.

Also Known As

GHSA-82j6-4fq7-fx62

GO-2026-5238

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