CVE-2026-10103— Authenticated remote cluster can modify or delete posts it does not own in Mattermost Connected Workspaces shared channels
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，该漏洞源于未在共享通道入站同步处理器中验证帖子所有权，可能导致经过身份验证的远程集群通过引用与远程共享的通道中任意帖子ID的特制同步消息，修改或删除由本地用户或其他远程用户创作的帖子。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、10.11.19及之前的10.11.x版本。
Possible ATT&CK Techniques 1 AI
T1133 · External Remote ServicesAffected 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-2026-10103
Vulnerability Information
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Vulnerability Title
Authenticated remote cluster can modify or delete posts it does not own in Mattermost Connected Workspaces shared channels
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 verify post ownership in the shared channel inbound sync handler, which allows an authenticated remote cluster to modify or delete posts authored by local users or other remotes via crafted sync messages referencing arbitrary post IDs in channels shared with that remote.. Mattermost Advisory ID: MMSA-2026-00689
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:N
Source: CVE Program / CVE List V5
Vulnerability Type
通过用户控制密钥绕过授权机制
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，该漏洞源于未在共享通道入站同步处理器中验证帖子所有权，可能导致经过身份验证的远程集群通过引用与远程共享的通道中任意帖子ID的特制同步消息，修改或删除由本地用户或其他远程用户创作的帖子。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、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-2026-10103
| # | POC Description | Source Link | Shenlong Link |
|---|
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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-2026-10085 | 5.4 MEDIUM | Ordinary group/direct message member can enable group_constrained and remove all channel p |
| 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-2026-9820 | 3.8 LOW | Mattermost schemes teams endpoint exposes private team invite IDs |
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