Medium severity · published Jul 17, 2026
CVE-2026-9602
Mattermost Desktop App crashes when malformed arguments are provided to some exposed IPC methods
6.5
CVSS
0.4%
EPSS
No
On KEV
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
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 36% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MA
Mattermost · Mattermost
through 6.0.2; through 5.6.13 · source: vendor
MD
Mattermost Desktop · Mattermost
before 5.13.7; 6.0.0 through 6.0.2; 6.2.0 before 6.2.1 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-9602
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-9602
Vendor Advisory
https://mattermost.com/security-updates
More from Mattermost
9.9
CVE-2026-4858
Path traversal in integration action URL leading to arbitrary API execution via system admin’s auth token.
9.9
CVE-2025-12421
Account Takeover via Code Exchange Endpoint
9.9
CVE-2025-12419
Account takeover on OAuth/OpenID-enabled servers
9.9
CVE-2025-4981
Path Traversal Leading to RCE by Any Authenticated Mattermost User
9.6
CVE-2024-39777
Malicious remote can invite itself to an arbitrary local channel