CVE-2026-10085— Ordinary group/direct message member can enable group_constrained and remove all channel participants
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，该漏洞源于未将group_constrained频道标志限制到支持组同步的公共和私有频道，导致普通群组或直接消息成员可以通过频道补丁API移除对话中的所有参与者。以下版本受到影响：11.7.2及之前的11.7.x版本、11.6.4及之前的11.6.x版本和10.11.19及之前的10.11.x版本。
Possible ATT&CK Techniques 3 AI
T1484 · Domain or Tenant Policy Modification T1136 · Create Account T1098 · Account ManipulationAffected Version Matrix 7
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| Mattermost | Mattermost | 11.7.0≤ 11.7.2 |
affected |
11.6.0≤ 11.6.4 |
affected | ||
10.11.0≤ 10.11.19 |
affected | ||
11.8.0 |
unaffected | ||
11.7.3 |
unaffected | ||
11.6.5 |
unaffected | ||
10.11.20 |
unaffected |
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I. Basic Information for CVE-2026-10085
Vulnerability Information
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Vulnerability Title
Ordinary group/direct message member can enable group_constrained and remove all channel participants
Source: CVE Program / CVE List V5
Vulnerability Description
Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to restrict the group_constrained channel flag to public and private channels that support group synchronization, which allows an ordinary group or direct message member to remove all participants from the conversation via the channel patch API.. Mattermost Advisory ID: MMSA-2026-00688
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制缺失
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，该漏洞源于未将group_constrained频道标志限制到支持组同步的公共和私有频道，导致普通群组或直接消息成员可以通过频道补丁API移除对话中的所有参与者。以下版本受到影响：11.7.2及之前的11.7.x版本、11.6.4及之前的11.6.x版本和10.11.19及之前的10.11.x版本。
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 ~ 11.7.2 | - |
|
II. Public POCs for CVE-2026-10085
| # | POC Description | Source Link | Shenlong Link |
|---|
AI-Generated POC
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Same Patch Batch · Mattermost · 2026-07-13 · 10 CVEs total
| CVE-2026-6850 | 6.5 MEDIUM | Crafted message attachment causes client-side denial of service via markdown parser regex |
| CVE-2026-10106 | 6.5 MEDIUM | Unauthorized users can trigger interactive post actions in private channels via action coo |
| CVE-2026-9571 | 5.9 MEDIUM | Deactivated user accounts can continue to obtain valid OAuth access tokens via refresh tok |
| CVE-2026-9597 | 5.4 MEDIUM | Deactivated guest accounts can authenticate via magic-link token in Mattermost REST API lo |
| CVE-2026-9708 | 4.9 MEDIUM | Incoming webhook user attribution via unvalidated webhook owner |
| CVE-2026-6541 | 4.3 MEDIUM | Unscoped updates to other playbooks' metric configuration |
| CVE-2026-9824 | 4.3 MEDIUM | Remote cluster metadata enumeration via /share-channel autocomplete |
| CVE-2026-10103 | 4.3 MEDIUM | Authenticated remote cluster can modify or delete posts it does not own in Mattermost Conn |
| CVE-2026-9820 | 3.8 LOW | Mattermost schemes teams endpoint exposes private team invite IDs |
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