CVE-2026-26230— Team Admin Privilege Escalation to Demote Members to Guest
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I. Basic Information for CVE-2026-26230
Vulnerability Information
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Vulnerability Title
Team Admin Privilege Escalation to Demote Members to Guest
Source: NVD (National Vulnerability Database)
Vulnerability Description
Mattermost versions 10.11.x <= 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N
Source: NVD (National Vulnerability Database)
Vulnerability Type
授权机制不正确
Source: NVD (National Vulnerability Database)
Vulnerability Title
Mattermost 安全漏洞
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 10.11.10及之前的10.11.x版本存在安全漏洞，该漏洞源于未正确验证团队成员角色API端点中的权限要求，可能导致团队管理员将成员降级为访客角色。
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 | 10.11.0 ~ 10.11.10 | - |
II. Public POCs for CVE-2026-26230
| # | POC Description | Source Link | Shenlong Link |
|---|
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Same Patch Batch · Mattermost · 2026-03-16 · 21 CVEs total
| CVE-2026-2476 | 7.6 HIGH | MS Teams plugin sensitive config values not properly masked in support packets |
| CVE-2026-24458 | 7.5 HIGH | DoS attack via login attempts with multi-megabyte passwords |
| CVE-2026-2462 | 6.6 MEDIUM | Admin RCE via Malicious Plugin Upload on CI Test Instances |
| CVE-2026-2454 | 5.8 MEDIUM | DoS in Calls plugin via malformed msgpack in websocket request. |
| CVE-2026-2456 | 5.3 MEDIUM | Denial of Service via Unbounded Memory Allocation in Integration Actions |
| CVE-2026-2455 | 4.3 MEDIUM | SSRF bypass via IPv4-mapped IPv6 literals |
| CVE-2026-21386 | 4.3 MEDIUM | Private channel enumeration via /mute slash command |
| CVE-2026-25780 | 4.3 MEDIUM | Memory Exhaustion via Malformed DOC File Upload |
| CVE-2026-4265 | 4.3 MEDIUM | Guest user can upload files without permission across teams |
| CVE-2026-25783 | 4.3 MEDIUM | Denial of service via malformed User-Agent header in getBrowserVersion |
| CVE-2026-24692 | 4.3 MEDIUM | Guest users can bypass read permissions via search API |
| CVE-2026-26304 | 4.3 MEDIUM | Permission Bypass in Playbook Run Creation |
| CVE-2026-2578 | 4.3 MEDIUM | Information Disclosure via WebSocket Event When Deleting Unrevealed Burn on Read Posts |
| CVE-2026-26246 | 4.3 MEDIUM | Memory Exhaustion via Malformed PSD File Upload |
| CVE-2026-2458 | 4.3 MEDIUM | Unauthorized channel enumeration in private teams after member removal |
| CVE-2026-2457 | 4.3 MEDIUM | WebSocket Message Spoofing via Permalink Embed Manipulation |
| CVE-2026-2461 | 4.3 MEDIUM | Missing authorization check allows unauthorized modification of other users' comments on a |
| CVE-2026-2463 | 4.3 MEDIUM | Unauthorized access to invite ID during team creation |
| CVE-2026-1629 | 4.3 MEDIUM | Permalink Preview Information Disclosure After Permission Revocation |
| CVE-2026-22545 | 3.1 LOW | Password Change Bypass via Auth Switch Endpoint |
IV. Related Vulnerabilities
Same product: Mattermost
- CVE-2026-3590
Race Condition in Guest Magic Link Authentication Allows Tok - CVE-2026-28741
CSRF Protection Bypass Allows Updating a User's Authenticati - CVE-2026-27769
Connected Workspaces: Malicious remote server can manipulate - CVE-2026-24661
Unbounded Request Body Read in MS Teams Plugin {{/changes}} - CVE-2026-21388
Unbounded Request Body Read in MS Teams Plugin {{/lifecycle}
Same vendor: Mattermost
- CVE-2026-3590
Race Condition in Guest Magic Link Authentication Allows Tok - CVE-2026-28741
CSRF Protection Bypass Allows Updating a User's Authenticati - CVE-2026-27769
Connected Workspaces: Malicious remote server can manipulate - CVE-2026-24661
Unbounded Request Body Read in MS Teams Plugin {{/changes}} - CVE-2026-21388
Unbounded Request Body Read in MS Teams Plugin {{/lifecycle}
Same weakness: CWE-863
- CVE-2026-42571
Privilege Escalation Attack affecting Pelican Web UI - CVE-2025-15633
HCL BigFix WebUI is affected by an improper authorization vu - CVE-2026-42296
Argo Workflows has incomplete fix for CVE-2026-31892: hostNe - CVE-2025-66170
Apache CloudStack: Any user can list backups that they shoul - CVE-2026-41903
FreeScout IDOR Vulnerability: PERM_EDIT_USERS allows modifyi
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