CVE-2021-24018: 
FortiOS vulnerability analysis and mitigation

A buffer underwrite vulnerability (CVE-2021-24018) was discovered in the firmware verification routine of FortiOS versions before 7.0.1. This vulnerability was disclosed in July 2021 and affects Fortinet's FortiOS operating system (NVD, MITRE).

The vulnerability is classified as a buffer underwrite (also known as buffer underflow) issue in the firmware verification routine. This type of vulnerability occurs when a product writes to a buffer using an index or pointer that references a memory location prior to the beginning of the buffer (CWE). The vulnerability has been assigned a base CVSS score indicating its severity level.

If successfully exploited, this vulnerability could allow an attacker located in the adjacent network to potentially execute arbitrary code via a specifically crafted firmware image (MITRE). The impact could include system compromise, unauthorized code execution, and potential control over the affected FortiOS system.

Fortinet has addressed this vulnerability in FortiOS version 7.0.1 and later releases. Users are strongly advised to upgrade to a patched version to mitigate this security risk (CERT-FR).