CVE-2024-21762
CVE-2024-21762 is a security flaw in Fortinet FortiOS, the operating system on Fortinet’s FortiGate firewalls. Attackers can run their own code on Fortinet FortiOS from anywhere, without logging in. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 9 Feb 2024, and says ransomware gangs have used it.[1]
Fortinet FortiOS is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Fixed in version 2.0.14, 7.0.15, 7.2.9 and 7.4.3 and others.
Description
CISA calls it an out-of-bound write in Fortinet FortiOS. In its words: “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.”[1]
The CVE record adds: “A out-of-bounds write vulnerability in Fortinet FortiOS 7.4.0 through 7.4.2, FortiOS 7.2.0 through 7.2.6, FortiOS 7.0.0 through 7.0.13, FortiOS 6.4.0 through 6.4.14, FortiOS 6.2.0 through 6.2.15, FortiOS 6.0 all versions, FortiProxy 7.4.0 through 7.4.2, FortiProxy 7.2.0 through 7.2.8, FortiProxy 7.0.0 through 7.0.14, FortiProxy 2.0.0 through 2.0.13, FortiProxy 01.02 all versions, FortiProxy 1.2 all versions, FortiProxy 01.01 all versions, FortiProxy 1.1 all versions, FortiProxy 01.00 all versions allows attacker to execute unauthorized code or commands via specifically crafted requests”[2]
The underlying weakness is out-of-bounds write (CWE-787), in MITRE’s list of common software weaknesses.
It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record lists these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| fortiproxy | 2.0.14 |
| fortiproxy | 7.0.15 |
| fortiproxy | 7.2.9 |
| fortiproxy | 7.4.3 |
| fortios | 6.2.16 |
| fortios | 6.4.15 |
| fortios | 7.0.14 |
| fortios | 7.2.7 |
Most families won’t have Fortinet FortiOS; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 9 Feb 2024, within a day of it being made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 16 Feb 2024 to fix it.[1] CISA says ransomware gangs have used it.
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 85%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
Fortinet has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.”[1]
- Check whether you use it.Fortinet FortiOS is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed (fixed in version 2.0.14, 7.0.15, 7.2.9 and 7.4.3 and others), or not in use. CISA gave US government agencies until 16 Feb 2024 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks, noting that ransomware gangs have used it.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 85%.[4] |
See also
Other Fortinet FortiOS flaws
- CVE-2025-68686: exposure of sensitive information to an unauthorized actor ·
- CVE-2019-6693: use of hard-coded credentials ·
- CVE-2022-41328: path traversal ·
- CVE-2022-42475: heap-based buffer overflow ·
- CVE-2021-44168: arbitrary file download ·
- CVE-2020-12812: SSL VPN improper authentication ·
Other Fortinet flaws
- CVE-2025-61624, Fortinet products: path traversal ·
- CVE-2026-104286, Fortinet FortiMail: path traversal ·
- CVE-2025-25249, Fortinet products: heap-based buffer overflow ·
- CVE-2026-39808, Fortinet FortiSandbox: OS command injection ·
- CVE-2026-25089, Fortinet FortiSandbox: OS command injection ·
Other out-of-bounds write flaws
- CVE-2026-86950, Apple devices: out-of-bounds write ·
- CVE-2026-53266, Linux Kernel: out-of-bounds write ·
- CVE-2026-87491, Chrome and other Chromium browsers: out of bounds write ·
- CVE-2026-53362, Linux Kernel: unspecified ·
- CVE-2022-0995, Linux Kernel: out-of-bounds write ·
Every Fortinet flaw on CISA’s list · Everything added in February 2024
References
- ^ Cybersecurity and Infrastructure Security Agency. “Fortinet FortiOS Out-of-Bound Write Vulnerability”. Known Exploited Vulnerabilities Catalog, added 9 Feb 2024.
- ^ National Institute of Standards and Technology. “CVE-2024-21762 Detail”. National Vulnerability Database, published 9 Feb 2024.
- ^ Fortinet. Advisories and fixes: fortiguard.fortinet.com, fortiguard.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.846, percentile 99.7, 31 Oct 2026.
- CVE Program. “CVE-2024-21762”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.