CVE-2026-6347— Mattermost Calls plugin exposes TURN server credentials in plaintext in support packets
Possible ATT&CK Techniques 1AI
T1530 · Data from Cloud StorageAffected Version Matrix 7
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| Mattermost | Mattermost | 11.5.0≤ 11.5.1 | affected |
10.11.0≤ 10.11.13 | affected | ||
11.4.0≤ 11.4.3 | affected | ||
11.6.0 | unaffected | ||
11.5.2 | unaffected | ||
10.11.14 | unaffected | ||
11.4.4 | unaffected |
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I. Basic Information for CVE-2026-6347
Vulnerability Information
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Vulnerability Title
Mattermost Calls plugin exposes TURN server credentials in plaintext in support packets
Source: NVD (National Vulnerability Database)
Vulnerability Description
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
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:L
Source: NVD (National Vulnerability Database)
Vulnerability Type
信息暴露
Source: NVD (National Vulnerability Database)
Vulnerability Title
Mattermost 信息泄露漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Mattermost是美国Mattermost公司的一个开源协作平台。 Mattermost 11.5.1及之前的11.5.x版本、10.11.13及之前的10.11.x版本和11.4.3及之前的11.4.x版本存在信息泄露漏洞，该漏洞源于Mattermost Calls插件中未能清理敏感配置字段，可能导致有权访问支持包的攻击者通过导出的插件配置中的明文值获取TURN服务器凭据。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| Mattermost | Mattermost | 11.5.0 ~ 11.5.1 | - |
II. Public POCs for CVE-2026-6347
| # | POC Description | Source Link | Shenlong Link |
|---|
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Same Patch Batch · Mattermost · 2026-05-18 · 21 CVEs total
| CVE-2026-6346 | 8.7 HIGH | Sensitive credentials exposed in plaintext in Mattermost support packets |
| CVE-2026-3471 | 6.5 MEDIUM | Opening a window with {{javascript:alert()}} as URL causes crash in the Mattermost Desktop |
| CVE-2026-3117 | 6.5 MEDIUM | Instance and webhook GitLab plugin commands were able to be run by non-admin users |
| CVE-2026-5163 | 6.5 MEDIUM | Missing authorization check in AI message rewrite endpoint allows access to private thread |
| CVE-2026-6345 | 6.5 MEDIUM | Prevent password disclosure and force reset during Slack import |
| CVE-2026-28732 | 4.3 MEDIUM | Slash command trigger-word update allowed command hijacking |
| CVE-2026-6343 | 4.3 MEDIUM | Mattermost Playbooks Plugin fails to enforce view permissions in list endpoints, allowing |
| CVE-2026-28759 | 4.3 MEDIUM | Insufficient authorization in shared channel membership sync allows remote cluster to remo |
| CVE-2026-2325 | 4.3 MEDIUM | Improper Input Validation in MS Teams Meetings API Handler |
| CVE-2026-6339 | 4.3 MEDIUM | Missing request origin validation on burn-on-read reveal endpoint |
| CVE-2026-6340 | 4.3 MEDIUM | Memory Exhaustion via Malicious 7zip File Upload |
| CVE-2026-6341 | 4.3 MEDIUM | Incomplete group locking implementation |
| CVE-2026-6342 | 4.3 MEDIUM | Group prefix matching bypass for subscriptions |
| CVE-2026-3637 | 4.3 MEDIUM | Mattermost fails to enforce create_post permission when editing posts |
| CVE-2026-3495 | 3.8 LOW | Unescaped variables during error page composition |
| CVE-2026-4273 | 3.7 LOW | Insufficient token rotation validation in remote cluster invite confirmation |
| CVE-2026-4643 | 3.5 LOW | Calling window.close() from server-side content causes crash in the Mattermost Desktop App |
| CVE-2026-6333 | 3.5 LOW | SSRF via Host Header Spoofing in Custom Slash Commands |
| CVE-2026-4286 | 3.1 LOW | Playbooks Plugin fails to validate team transfers, allowing unauthorized removal of member |
| CVE-2026-6334 | 3.1 LOW | OAuth authorization code client binding not enforced during token redemption in Mattermost |
IV. Related Vulnerabilities
Same product: Mattermost
- CVE-2026-4915
Server panic via outgoing webhook responses - CVE-2026-28735
GitHub OAuth Scope Validation - CVE-2026-4635
Persistent notification timing attack causing server denial - CVE-2026-3473
Improper file ownership validation in the Boards API allows - CVE-2026-4646
Insufficient input validation in GitHub plugin API causes de
Same vendor: Mattermost
- CVE-2026-4915
Server panic via outgoing webhook responses - CVE-2026-28735
GitHub OAuth Scope Validation - CVE-2026-4635
Persistent notification timing attack causing server denial - CVE-2026-3473
Improper file ownership validation in the Boards API allows - CVE-2026-4646
Insufficient input validation in GitHub plugin API causes de
Same weakness: CWE-200
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NVIDIA GPU Display Driver for Linux Race Condition 漏洞 - CVE-2026-9352
NousResearch hermes-agent Messaging Gateway local.py _make_r - CVE-2026-9349
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authentik: Non-admin user can retrieve confidential OAuth cl - CVE-2026-3636
Sanitize team member data returned by API
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