CVE-2024-55599: 
FortiOS vulnerability analysis and mitigation

An Improperly Implemented Security Check for Standard vulnerability (CVE-2024-55599) was discovered in FortiOS and FortiProxy systems. The vulnerability, identified as CWE-358, affects multiple versions of FortiOS (versions 7.6.0, 7.4.7 and below, 7.0 all versions, 6.4 all versions) and FortiProxy (version 7.6.1 and below, 7.4.8 and below, 7.2 all versions, 7.0 all versions). The issue was internally discovered and reported by Jonathan Hurley from the Fortinet Consulting System Engineer team, with initial publication on July 8, 2025 (Fortinet Advisory).

The vulnerability is characterized as an Improperly Implemented Security Check for Standard (CWE-358) that specifically affects the DNS filter functionality. The issue received a CVSS v3.1 Base Score of 5.3 (Medium severity) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N, indicating network accessibility with low attack complexity and no required privileges or user interaction (NVD).

The vulnerability allows remote unauthenticated users to bypass the DNS filter specifically when using Apple devices. This improper access control could potentially compromise the security measures implemented by the DNS filtering system (Fortinet Advisory).

Fortinet has released patches and provided specific upgrade paths for affected systems: FortiOS 7.6.0 users should upgrade to 7.6.1 or above, FortiOS 7.4.0-7.4.7 users should upgrade to 7.4.8 or above, and FortiOS 7.2.0-7.2.10 users should upgrade to 7.2.11 or above. FortiProxy users on version 7.6.0-7.6.1 should upgrade to 7.6.2 or above, and those on 7.4.0-7.4.8 should upgrade to 7.4.9 or above. Users of FortiSASE 24.4.a have been automatically remediated in version 24.4.b (Fortinet Advisory).