Exploited vulnerability · CISA KEV

Is CVE-2024-21762 exploited? Yes: in CISA KEV since 9 Feb 2024

Gociux · Fortinet FortiOS · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2024-21762, Fortinet FortiOS Out-of-Bound Write Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 9 Feb 2024, the day it was published. It is known to be used in ransomware campaigns. It affects Fortinet FortiOS, an internet-facing product of the kind attackers use for initial access. If you run it, CISA's required action is: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

What it is

Fortinet FortiOS contains an out-of-bound write vulnerability that allows a remote unauthenticated attacker to execute code or commands via specially crafted HTTP requests.

What to do

1. Check whether you run it. Look for FortiOS in your asset inventory, including appliances and cloud images. Stack check lists every exploited Fortinet CVE at once.
2. Apply the fix. Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 9 Feb 2024.
4. Get told next time. Email alerts when CISA adds a CVE for Fortinet.

Other exploited CVEs in FortiOS

• CVE-2025-68686: Fortinet FortiOS Exposure of Sensitive Information to an Unauthorized Actor Vulnerability (27 Jul 2026)
• CVE-2019-6693: Fortinet FortiOS Use of Hard-Coded Credentials Vulnerability (25 Jun 2025)
• CVE-2022-41328: Fortinet FortiOS Path Traversal Vulnerability (14 Mar 2023)
• CVE-2022-42475: Fortinet FortiOS Heap-Based Buffer Overflow Vulnerability (13 Dec 2022)
• CVE-2021-44168: Fortinet FortiOS Arbitrary File Download (10 Dec 2021)
• CVE-2019-5591: Fortinet FortiOS Default Configuration Vulnerability (3 Nov 2021)

References

• fortiguard.fortinet.com/psirt/FG-IR-24-015
• nvd.nist.gov/vuln/detail/CVE-2024-21762

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in February 2024 · Fortinet scorecard · act-now radar.