CVE-2021-42755: Fortinet FortiOS

Medium severity, CVSS 4.3. EPSS: 0.4% chance of exploitation in the next 30 days.

An integer overflow / wraparound vulnerability [CWE-190] in FortiSwitch 7.0.2 and below, 6.4.9 and below, 6.2.x, 6.0.x; FortiRecorder 6.4.2 and below, 6.0.10 and below; FortiOS 7.0.2 and below, 6.4.8 and below, 6.2.10 and below, 6.0.x; FortiProxy 7.0.0, 2.0.6 and below, 1.2.x, 1.1.x, 1.0.x; FortiVoiceEnterprise 6.4.3 and below, 6.0.10 and below dhcpd daemon may allow an unauthenticated and network adjacent attacker to crash the dhcpd deamon, resulting in potential denial of service.

Affected products

• Fortinet FortiOS: version 5.4.0 only; version 5.4.1 only; version 5.4.2 only; version 5.4.3 only; version 5.4.4 only; version 5.4.5 only; …
• Fortinet FortiProxy: from 1.0.0, up to and including 1.0.7; from 1.1.0, up to and including 1.1.6; from 1.2.0, up to and including 1.2.13; from 2.0.0, up to and including 2.0.6; version 7.0.0 only
• Fortinet Fortirecorder Firmware: version 6.0.0 only; version 6.0.1 only; version 6.0.2 only; version 6.0.3 only; version 6.0.4 only; version 6.0.5 only; …
• Fortinet Fortiswitch: from 6.0.0, up to and including 6.0.7; from 6.2.0, up to and including 6.2.7; from 6.4.0, up to and including 6.4.9; from 7.0.0, up to and including 7.0.2
• Fortinet Fortivoice: version 5.3.0 only; version 5.3.1 only; version 5.3.2 only; version 5.3.3 only; version 5.3.4 only; version 5.3.5 only; …

Published 2022-07-18. Last modified 2026-06-17.