Is CVE-2026-4643 in the CISA KEV catalog?

No. CVE-2026-4643 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-4643?

CVE-2026-4643 has a CVSS v3 base score of 3.5 (LOW).

What is the EPSS score for CVE-2026-4643?

CVE-2026-4643 has an EPSS score of 0.17% (7th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-4643?

Upgrade Mattermost to 6.2.0 or later.

CVE & CISA-KEV Catalog

CVE-2026-4643

LOW

3.5

CVSS v3

NVD

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

CWE-754

How to fix

Remediation Available

MattermostWindows application

Affected:6.1.0 6.2.0Fixed in:6.2.0Mattermost, Inc.

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityLow

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

Exploit Intelligence

0.17%probability of exploitation in 30 days

7thpercentile

Low risk: more likely to be exploited than 7% of all known CVEs.

References

Vendor Advisory1

mattermost.com

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-05.