How severe is CVE-2026-4643?

CVE-2026-4643 has a CVSS 3.x base score of 3.5, rated low severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2026-4643 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (7th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-4643?

CVE-2026-4643 affects Mattermost Mattermost Desktop. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-4643?

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

Does CVE-2026-4643 have an EU (EUVD) identifier?

Yes. CVE-2026-4643 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30758.

When was CVE-2026-4643 published?

CVE-2026-4643 was published on 2026-05-18 and last updated on 2026-06-17.

CVE-2026-4643

CVE-2026-4643 is a low-severity vulnerability in Mattermost Mattermost Desktop with a CVSS 3.x base score of 3.5. 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-754.

Key facts

Severity: Low (CVSS 3.x base score 3.5)
EPSS exploit prediction: 0% (7th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-30758
Weakness: CWE-754
Affected product: Mattermost Mattermost Desktop
Published: 2026-05-18
Last modified: 2026-06-17

Description

Mattermost Desktop App versions <=6.1 6.0.1 5.4.13.0 fail to prevent server-rendered content from closing an underlying application view in the Mattermost Desktop App which allows a malicious server or plugin to crash the desktop client via invoking {{window.close()}} in the renderer context, leading to a denial of service condition at the client level. Mattermost Advisory ID: MMSA-2026-00633

Frequently asked questions

What is CVE-2026-4643?: Mattermost Desktop App versions <=6.1 6.0.1 5.4.13.0 fail to prevent server-rendered content from closing an underlying application view in the Mattermost Desktop App which allows a malicious server or plugin to crash the desktop client via invoking {{window.close()}} in the renderer context, leading to a denial of service condition at the client level. Mattermost Advisory ID: MMSA-2026-00633
How severe is CVE-2026-4643?: CVE-2026-4643 has a CVSS 3.x base score of 3.5, rated low severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2026-4643 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (7th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-4643?: CVE-2026-4643 affects Mattermost Mattermost Desktop. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-4643?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-4643 have an EU (EUVD) identifier?: Yes. CVE-2026-4643 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30758.
When was CVE-2026-4643 published?: CVE-2026-4643 was published on 2026-05-18 and last updated on 2026-06-17.

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-2026-8683 — Medium (CVSS 6.5): Mattermost Desktop App versions <=6.1 5.5.13.0 fail to account for attempting to open extremely long URLs in the…

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