Mattermost group syncable endpoints allow privilege escalation via scheme_admin

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Summary

CVECVE-2026-7387
StatePUBLISHED
AssignerMattermost
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-12 17:16:27 UTC
Updated2026-06-18 14:46:51 UTC
DescriptionMattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 Mattermost fails to require role-management authorization when setting the scheme_admin flag on group syncable link and patch endpoints, which allows a user with group-link permissions to escalate themselves and group members to team or channel admin via crafted API requests.. Mattermost Advisory ID: MMSA-2026-00665

Risk And Classification

Primary CVSS: v3.1 8.8 HIGH from [email protected]

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

EPSS: 0.002980000 probability, percentile 0.212280000 (date 2026-06-22)

Problem Types: CWE-863 | CWE-863 CWE-863: Incorrect Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNACVSS8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

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

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

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 11.6.0 11.6.1 semver Not specified
CNA Mattermost Mattermost affected 11.5.0 11.5.4 semver Not specified
CNA Mattermost Mattermost affected 10.11.0 10.11.15 semver Not specified
CNA Mattermost Mattermost affected 10.11.0 10.11.16 semver Not specified
CNA Mattermost Mattermost unaffected 11.7.0 Not specified
CNA Mattermost Mattermost unaffected 11.6.2 Not specified
CNA Mattermost Mattermost unaffected 11.5.5 Not specified
CNA Mattermost Mattermost unaffected 10.11.16 Not specified
CNA Mattermost Mattermost unaffected 10.11.17 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: winfunc (en)

Additional Advisory Data

Solutions

CNA: Update Mattermost to versions 11.7.0, 11.6.2, 11.5.5, 10.11.16, 10.11.17 or higher.

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