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CVE-2026-6739— Mattermost: Delegated admins could patch protected default system roles

Quick assessment

Affected
Mattermost Mattermost
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Mattermost是美国Mattermost公司开源的一个开源协作平台。 Mattermost存在授权问题漏洞，该漏洞源于修补受保护的默认系统角色时未要求系统级权限，可能导致经过身份验证的用户通过角色修补API更改内置角色权限，从而提升权限。

CVSS 6.7 · Medium EPSS 0.46% · P39

Affected Version Matrix 9

VendorProduct Version RangeStatus
Mattermost Mattermost 11.6.0≤ 11.6.1 affected
11.5.0≤ 11.5.4 affected
10.11.0≤ 10.11.15 affected
10.11.0≤ 10.11.16 affected
11.7.0 unaffected
11.6.2 unaffected
11.5.5 unaffected
10.11.16 unaffected
… +1 more rows
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I. Basic Information for CVE-2026-6739

Vulnerability Information
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Vulnerability Title
Mattermost: Delegated admins could patch protected default system roles
Source: CVE Program / CVE List V5
Vulnerability 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 fail to require system-level permission when patching protected default system roles, which allows authenticated users with delegated user-management permissions to escalate privileges by altering built-in role permissions via the role patch API.. Mattermost Advisory ID: MMSA-2026-00656
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制不正确
Source: CVE Program / CVE List V5
Vulnerability Title
Mattermost 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Mattermost是美国Mattermost公司开源的一个开源协作平台。 Mattermost存在授权问题漏洞，该漏洞源于修补受保护的默认系统角色时未要求系统级权限，可能导致经过身份验证的用户通过角色修补API更改内置角色权限，从而提升权限。
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 11.6.0 ~ 11.6.1 -

II. Public POCs for CVE-2026-6739

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III. Intelligence Information for CVE-2026-6739

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Same Patch Batch · Mattermost · 2026-06-12 · 7 CVEs total

CVE-2026-7387 8.8 HIGH Mattermost group syncable endpoints allow privilege escalation via scheme_admin
CVE-2026-6961 7.6 HIGH CVE-2026-6961: Path traversal via unsanitized FileInfo.Name in Mattermost federation sync
CVE-2026-7184 6.5 MEDIUM Mattermost Remote Cluster PATCH API Leaks Authentication Tokens
CVE-2026-6046 5.3 MEDIUM Plugin bot username conflict allows user account to be used as bot identity in Mattermost
CVE-2026-6689 4.3 MEDIUM *Missing* {{invite_user}} *permission check on team creation allows unprivileged users to
CVE-2026-3433 4.3 MEDIUM Mattermost fails to scope role_updated websocket events to authorized team and channel mem

IV. Related Vulnerabilities

Same product: Mattermost
Same vendor: Mattermost
Same weakness: CWE-863

V. Comments for CVE-2026-6739

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