CVE-2026-27769— Connected Workspaces: Malicious remote server can manipulate arbitrary user's status
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公司的一个开源协作平台。 Mattermost 10.11.12及之前的10.11.x版本存在安全漏洞，该漏洞源于未验证用户所有权，可能导致恶意远程服务器更改本地用户的显示状态。
Possible ATT&CK Techniques 1 AI
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I. Basic Information for CVE-2026-27769
Vulnerability Information
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Vulnerability Title
Connected Workspaces: Malicious remote server can manipulate arbitrary user's status
Source: CVE Program / CVE List V5
Vulnerability Description
Mattermost versions 10.11.x <= 10.11.12 fail to validate whether users were correctly owned by the correct Connected Workspace which allows a malicious remote server connected using the Conntexted Workspaces feature to change the displayed status of local users via the Connected Workspaces API.. Mattermost Advisory ID: MMSA-2026-00603
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制缺失
Source: CVE Program / CVE List V5
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 10.11.12及之前的10.11.x版本存在安全漏洞，该漏洞源于未验证用户所有权，可能导致恶意远程服务器更改本地用户的显示状态。
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 ~ 10.11.12 | - |
|
II. Public POCs for CVE-2026-27769
| # | POC Description | Source Link | Shenlong Link |
|---|
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Same Patch Batch · Mattermost · 2026-04-15 · 3 CVEs total
| CVE-2026-28741 | 6.8 MEDIUM | CSRF Protection Bypass Allows Updating a User's Authentication Method |
| CVE-2026-3590 | 6.5 MEDIUM | Race Condition in Guest Magic Link Authentication Allows Token Reuse |
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V. Comments for CVE-2026-27769
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