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CVE-2026-10103— Authenticated remote cluster can modify or delete posts it does not own in Mattermost Connected Workspaces shared channels

CVSS 4.3 · Medium EPSS 0.14% · P4

Possible ATT&CK Techniques 1AI

T1133 · External Remote Services

Affected Version Matrix 7

VendorProductVersion RangeStatus
MattermostMattermost11.7.0≤ 11.7.2affected
11.6.0≤ 11.6.4affected
10.11.0≤ 10.11.19affected
11.8.0unaffected
11.7.3unaffected
11.6.5unaffected
10.11.20unaffected
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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: NVD (National Vulnerability Database)
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: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Source: NVD (National Vulnerability Database)
Vulnerability Type
通过用户控制密钥绕过授权机制
Source: NVD (National Vulnerability Database)
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

VendorProductAffected VersionsCPESubscribe
MattermostMattermost 11.7.0 ~ 11.7.2 -

II. Public POCs for CVE-2026-10103

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III. Intelligence Information for CVE-2026-10103

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Same Patch Batch · Mattermost · 2026-07-13 · 10 CVEs total

CVE-2026-68506.5 MEDIUMCrafted message attachment causes client-side denial of service via markdown parser regex
CVE-2026-101066.5 MEDIUMUnauthorized users can trigger interactive post actions in private channels via action coo
CVE-2026-95715.9 MEDIUMDeactivated user accounts can continue to obtain valid OAuth access tokens via refresh tok
CVE-2026-95975.4 MEDIUMDeactivated guest accounts can authenticate via magic-link token in Mattermost REST API lo
CVE-2026-100855.4 MEDIUMOrdinary group/direct message member can enable group_constrained and remove all channel p
CVE-2026-97084.9 MEDIUMIncoming webhook user attribution via unvalidated webhook owner
CVE-2026-65414.3 MEDIUMUnscoped updates to other playbooks' metric configuration
CVE-2026-98244.3 MEDIUMRemote cluster metadata enumeration via /share-channel autocomplete
CVE-2026-98203.8 LOWMattermost schemes teams endpoint exposes private team invite IDs

IV. Related Vulnerabilities

Same product: Mattermost
Same vendor: Mattermost
Same weakness: CWE-639

V. Comments for CVE-2026-10103

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