Mattermost Desktop App Missing IPC Sender Validation in Calls Leave Handler

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-12284
StatePUBLISHED
AssignerMattermost
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-17 16:17:21 UTC
Updated2026-09-18 13:46:33 UTC
DescriptionMattermost Desktop App versions <=6.2 6.2.2.0 fails to validate the IPC sender in the leaveCall handler which allows a malicious or compromised Mattermost server (or a user with script access to a connected server view) to disconnect an active call belonging to a different connected server via the desktopAPI.leaveCall IPC message. Mattermost Advisory ID: MMSA-2026-00699

Risk And Classification

Primary CVSS: v3.1 3.7 LOW from [email protected]

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

EPSS: 0.001310000 probability, percentile 0.030910000 (date 2026-09-20)

Problem Types: CWE-346 | CWE-346 CWE-346: Origin Validation Error

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary3.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1CNACVSS3.8LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mattermost Mattermost affected 6.2.2 semver Not specified
CNA Mattermost Mattermost unaffected 6.3.0 Not specified
CNA Mattermost Mattermost unaffected 6.2.3.0 Not specified

References

ReferenceSourceLinkTags
mattermost.com/security-updates [email protected] mattermost.com
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: Juho Forsén (en)

Additional Advisory Data

Solutions

CNA: Update Mattermost Desktop App to versions 6.3.0, 6.2.3.0 or higher.

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