CVE-2022-42475
CVE-2022-42475 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 13 Dec 2022, 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. Fortinet has published a fix or advice.
Description
CISA calls it a heap-based buffer overflow in Fortinet FortiOS. In its words: “Multiple versions of Fortinet FortiOS SSL-VPN contain a heap-based buffer overflow vulnerability which can allow an unauthenticated, remote attacker to execute arbitrary code or commands via specifically crafted requests.”[1]
The CVE record adds: “A heap-based buffer overflow vulnerability [CWE-122] in FortiOS SSL-VPN 7.2.0 through 7.2.2, 7.0.0 through 7.0.8, 6.4.0 through 6.4.10, 6.2.0 through 6.2.11, 6.0.15 and earlier and FortiProxy SSL-VPN 7.2.0 through 7.2.1, 7.0.7 and earlier may allow a remote unauthenticated attacker to execute arbitrary code or commands via specifically crafted requests.”[2]
The underlying weakness is CWE-197, 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 doesn’t list version ranges for it; Fortinet’s advisory has them[3]. CISA names the product as Fortinet FortiOS.
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 13 Dec 2022. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 3 Jan 2023 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 99%. 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 updates per vendor instructions.”[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, or not in use. CISA gave US government agencies until 3 Jan 2023 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 |
|---|---|
| CISA adds it to its catalog of flaws known to be used in attacks, noting that ransomware gangs have used it.[1] | |
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2] | |
| 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 99%.[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-2024-21762: out-of-bound write ·
- CVE-2022-41328: path traversal ·
- 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 ·
Added the same day
- CVE-2022-44698, Microsoft Defender: smartScreen security feature bypass ·
- CVE-2022-27518, Citrix Application Delivery Controller (ADC) and Gateway: authentication bypass ·
- CVE-2022-26501, Veeam Backup & Replication: remote code execution ·
- CVE-2022-26500, Veeam Backup & Replication: remote code execution ·
Every Fortinet flaw on CISA’s list · Everything added in December 2022
References
- ^ Cybersecurity and Infrastructure Security Agency. “Fortinet FortiOS Heap-Based Buffer Overflow Vulnerability”. Known Exploited Vulnerabilities Catalog, added 13 Dec 2022.
- ^ National Institute of Standards and Technology. “CVE-2022-42475 Detail”. National Vulnerability Database, published 2 Jan 2023.
- ^ Fortinet. Advisories and fixes: fortiguard.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.995, percentile 99.9, 31 Oct 2026.
- CVE Program. “CVE-2022-42475”. 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.