CVE-2026-4643Network attack vector

Client crash via renderer window.close invocation

Published May 18, 2026 · Updated May 18, 2026

Improper exception handling in Mattermost Desktop App 6.1.0, 6.0.1, and 5.4.13 and earlier allows remote authenticated users to crash the client. A renderer accepts server or plugin content that invokes window.close(), allowing it to close the underlying application view instead of rejecting the call. Exploitation requires a user to connect the desktop app to a malicious server or load content from a malicious plugin; the consequence is a client-level service interruption.

CVSS severity3.5
Low
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper exception handling in Mattermost Desktop App 6.1.0, 6.0.1, and 5.4.13 and earlier allows remote authenticated users to crash the client. A renderer accepts server or plugin content that invokes window.close(), allowing it to close the underlying application view instead of rejecting the call. Exploitation requires a user to connect the desktop app to a malicious server or load content from a malicious plugin; the consequence is a client-level service interruption.

The record

CVE
CVE-2026-4643
Published
May 18, 2026
Updated
May 18, 2026
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-754, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 18, 2026CVE publishedPublication date reported by the CVE source.
  2. May 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=5.4.13
  2. Affected versionversion=0 <=6.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=0 <=5.4.13; version=0 <=6.0.1

Published CVSS scores

3.5Mattermost, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-754Improper Check for Unusual or Exceptional Conditions
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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