CVE-2026-9602

Mattermost Desktop App crashes when malformed arguments are provided to some exposed IPC methods

MEDIUM

6.5

CVSS Score

Published: July 17, 2026 at 10:03 AM UTC

Updated: October 15, 2026 at 01:32 PM UTC

2 products affected across 1 vendorMattermost DesktopMattermost

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Severity

MEDIUM6.5

Exploit prediction

EPSS 0.4%

SSVC

No known exploit

Description

Mattermost Desktop App versions <=6.2 6.0.2 5.6.13.0 fail to validate payloads sent from the Mattermost Web App to the Desktop App which allows a malicious server owner to crash the Mattermost Desktop App via changing the payload of a method to a malformed one. Mattermost Advisory ID: MMSA-2026-00678

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Mattermost Desktop · Mattermost

95%

v < 5.13.76.0.0 ≤ v ≤ 6.0.26.2.0 ≤ v < 6.2.1

Affected range stops below 5.13.7, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.2.1, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.3, so it looks safe — our inference, not a vendor statement

Mattermost · Mattermost

90%

0 ≤ v ≤ 5.6.130 ≤ v ≤ 6.0.2

Vendor states this is fixed in 5.13.7.0 (unaffected)

Vendor states this is fixed in 6.2.1.0 (unaffected)

Vendor states this is fixed in 6.3.0 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://mattermost.com/security-updates

References (1)

Vendor Advisory

Source: cverecord

https://mattermost.com/security-updates

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUM[email protected]

Attack Vector: NETWORK
Complexity: LOW
Privileges: LOW
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusANALYZED

CWE

CWE-400

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