Group prefix matching bypass for subscriptions

MITRE NVD CVE.ORG JSON API Print: PDF PDF

Summary

CVECVE-2026-6342
StatePUBLISHED
AssignerMattermost
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-18 08:16:14 UTC
Updated2026-05-29 19:11:57 UTC
DescriptionMattermost Plugins versions <=11.5 11.1.5 10.13.11 11.3.4.0 fail to appropriately check for valid namespaces which allows plugin users to create subscriptions to groups that were not whitelisted via creating groups that share the same prefix as a whitelisted group. Mattermost Advisory ID: MMSA-2026-00601

Risk And Classification

Primary CVSS: v3.1 4.3 MEDIUM from [email protected]

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

EPSS: 0.000310000 probability, percentile 0.094680000 (date 2026-06-01)

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

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
3.1CNACVSS4.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

CVSS v3.1 Breakdown

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

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Mattermost Mattermost Server All All All All
Application Mattermost Mattermost Server All All All All
Application Mattermost Mattermost Server All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mattermost Mattermost affected 11.1.5 semver Not specified
CNA Mattermost Mattermost affected 10.13.11 semver Not specified
CNA Mattermost Mattermost affected 11.3.4 semver Not specified
CNA Mattermost Mattermost unaffected 11.6.0 Not specified
CNA Mattermost Mattermost unaffected 11.5.2 Not specified
CNA Mattermost Mattermost unaffected 10.11.14 Not specified
CNA Mattermost Mattermost unaffected 11.4.4 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: eahmed (en)

Additional Advisory Data

Solutions

CNA: Update Mattermost Plugins to versions 11.6.0, 11.5.2, 10.11.14, 11.4.4 or higher.

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