PatchSiren cyber security CVE debrief

CVE-2023-43686 Malwarebytes CVE debrief

CVE-2023-43686 is a medium-severity vulnerability (CVSS score of 6.2) affecting Malwarebytes 4.x and 5.x (and Nebula 2020-10-21 and later). The issue occurs when a large number of Firefox preference files cause the parser to ignore other browser configuration files, leading to a denial of service.

Vendor: Malwarebytes
Product: Malwarebytes 4.x and 5.x
CVSS: MEDIUM 6.2
CISA KEV: Not listed in stored evidence
Original CVE published: 2026-06-09
Original CVE updated: 2026-06-09
Advisory published: 2026-06-09
Advisory updated: 2026-06-09

Who should care

Users of Malwarebytes 4.x and 5.x (and Nebula 2020-10-21 and later) should be aware of this vulnerability and take necessary actions to mitigate the risk.

Technical summary

The vulnerability is caused by the parser ignoring other browser configuration files when a large number of Firefox preference files are present. This leads to a denial of service.

Defensive priority

MEDIUM

Recommended defensive actions

Users should update Malwarebytes to the latest version to ensure they have the necessary patches.
Administrators should review their Malwarebytes configurations to ensure they are not vulnerable to this issue.

Evidence notes

The CVE record [resourceLinkAnnotations:cve-org] and NVD detail [resourceLinkAnnotations:nvd] provide additional information about this vulnerability.

Official resources

CVE-2023-43686 was published on 2026-06-09T19:16:41.907Z and modified on 2026-06-09T20:16:30.320Z.