How severe is CVE-2026-9602?

CVE-2026-9602 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-9602 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-9602?

CVE-2026-9602 affects Mattermost Mattermost Desktop. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-9602?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-9602 published?

CVE-2026-9602 was published on 2026-07-17 and last updated on 2026-07-30.

CVE-2026-9602

CVE-2026-9602 is a medium-severity vulnerability in Mattermost Mattermost Desktop with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-400.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-400
Affected product: Mattermost Mattermost Desktop
Published: 2026-07-17
Last modified: 2026-07-30

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

Frequently asked questions

What is CVE-2026-9602?: 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
How severe is CVE-2026-9602?: CVE-2026-9602 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-9602 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-9602?: CVE-2026-9602 affects Mattermost Mattermost Desktop. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-9602?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-9602 published?: CVE-2026-9602 was published on 2026-07-17 and last updated on 2026-07-30.

References

https://mattermost.com/security-updates

Affected products (1)

cpe:2.3:a:mattermost:mattermost_desktop:*:*:*:*:*:*:*:*

More vulnerabilities in Mattermost Mattermost Desktop

CVE-2016-11064 — Critical (CVSS 9.8): An issue was discovered in Mattermost Desktop App before 3.4.0. Strings could be executed as code via injection.
CVE-2019-20856 — Critical (CVSS 9.8): An issue was discovered in Mattermost Desktop App before 4.3.0 on macOS. It allows dylib injection.
CVE-2019-20861 — High (CVSS 8.8): An issue was discovered in Mattermost Desktop App before 4.2.2. It allows attackers to execute arbitrary code via a…
CVE-2026-1046 — High (CVSS 7.6): Mattermost Desktop App versions <=6.0 6.2.0 5.2.13.0 fail to validate help links which allows a malicious Mattermost…
CVE-2020-14456 — High (CVSS 7.3): An issue was discovered in Mattermost Desktop App before 4.4.0. The Same Origin Policy is mishandled during…
CVE-2026-8075 — Medium (CVSS 6.5): Mattermost Desktop App versions <=6.2 5.5.13 6.0.2.0 fail to properly null check when checking for headers in the…

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