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CVE-2026-8823— User Manager can demote bot accounts to guest without bot-management permission

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 11.7.0及之前的11.7.x版本和10.11.17及之前的10.11.x版本存在授权问题漏洞，该漏洞源于降级用户为访客时未能验证机器人目标，可能导致低权限管理员通过标准降级用户API降级任意机器人账户。

CVSS 3.8 · Low EPSS 0.32% · P23

Possible ATT&CK Techniques 1 AI

T1078 · Valid Accounts

Affected Version Matrix 5

VendorProduct Version RangeStatus
Mattermost Mattermost 11.7.0≤ 11.7.0 affected
10.11.0≤ 10.11.17 affected
11.8.0 unaffected
11.7.1 unaffected
10.11.18 unaffected
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I. Basic Information for CVE-2026-8823

Vulnerability Information
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Vulnerability Title
User Manager can demote bot accounts to guest without bot-management permission
Source: CVE Program / CVE List V5
Vulnerability Description
Mattermost versions 11.7.x <= 11.7.0, 10.11.x <= 10.11.17 fail to validate bot targets when demoting users to guests which allows a lower-privileged administrator to degrade arbitrary bot accounts via the standard demote-user API.. Mattermost Advisory ID: MMSA-2026-00669
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: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 11.7.0及之前的11.7.x版本和10.11.17及之前的10.11.x版本存在授权问题漏洞，该漏洞源于降级用户为访客时未能验证机器人目标，可能导致低权限管理员通过标准降级用户API降级任意机器人账户。
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 11.7.0 ~ 11.7.0 -

II. Public POCs for CVE-2026-8823

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III. Intelligence Information for CVE-2026-8823

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Same Patch Batch · Mattermost · 2026-06-22 · 6 CVEs total

CVE-2026-6062 6.4 MEDIUM IDOR in Jira plugin subscription edit endpoint
CVE-2026-6673 6.4 MEDIUM Mattermost Jira plugin had unauthenticated {{/ac/installed}} lifecycle callback during pen
CVE-2026-5139 5.4 MEDIUM GitLab Plugin Allows Non-Admin Users to Modify Default Instance Configuration
CVE-2026-9162 4.3 MEDIUM Global session revocation does not invalidate active WebSocket connections
CVE-2026-8074 3.8 LOW Improper Permission Check Allows User Manager to Deactivate Bot Accounts

IV. Related Vulnerabilities

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

V. Comments for CVE-2026-8823

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