Ordinary group/direct message member can enable group_constrained and remove all channel participants

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Summary

CVECVE-2026-10085
StatePUBLISHED
AssignerMattermost
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-13 09:16:22 UTC
Updated2026-07-14 13:19:08 UTC
DescriptionMattermost 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

Risk And Classification

Primary CVSS: v3.1 5.4 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

EPSS: 0.001700000 probability, percentile 0.065930000 (date 2026-07-14)

Problem Types: CWE-862 | CWE-862 CWE-862: Missing Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
3.1CNACVSS5.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Mattermost Mattermost Server All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mattermost Mattermost affected 11.7.0 11.7.2 semver Not specified
CNA Mattermost Mattermost affected 11.6.0 11.6.4 semver Not specified
CNA Mattermost Mattermost affected 10.11.0 10.11.19 semver Not specified
CNA Mattermost Mattermost unaffected 11.8.0 Not specified
CNA Mattermost Mattermost unaffected 11.7.3 Not specified
CNA Mattermost Mattermost unaffected 11.6.5 Not specified
CNA Mattermost Mattermost unaffected 10.11.20 Not specified

References

ReferenceSourceLinkTags
mattermost.com/security-updates [email protected] mattermost.com Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: se1en (en)

Additional Advisory Data

Solutions

CNA: Update Mattermost to versions 11.8.0, 11.7.3, 11.6.5, 10.11.20 or higher.

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