Posting a malicious markdown image crashes the Mattermost Desktop App

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-8075
StatePUBLISHED
AssignerMattermost
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-17 11:17:15 UTC
Updated2026-07-17 15:01:06 UTC
DescriptionMattermost Desktop App versions <=6.2 5.5.13 6.0.2.0 fail to properly null check when checking for headers in the Mattermost Desktop App which allows any user to crash another channel members Desktop App via posting a malicious link with an embedded image that misses one of those headers. Mattermost Advisory ID: MMSA-2026-00668

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

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

EPSS: 0.002350000 probability, percentile 0.144490000 (date 2026-07-20)

Problem Types: CWE-754 | CWE-754 CWE-754: Improper Check for Unusual or Exceptional Conditions

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
3.1CNACVSS6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mattermost Mattermost affected 5.5.13 semver Not specified
CNA Mattermost Mattermost affected 6.0.2 semver Not specified
CNA Mattermost Mattermost unaffected 6.3.0 Not specified
CNA Mattermost Mattermost unaffected 5.13.6.0 Not specified
CNA Mattermost Mattermost unaffected 6.2.1.0 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: Jopraveen (en)

Additional Advisory Data

Solutions

CNA: Update Mattermost Desktop App to versions 6.3.0, 5.13.6.0, 6.2.1.0 or higher.

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