CVE-2026-21643
CVE-2026-21643 is a security flaw in Fortinet FortiClient EMS, Fortinet’s business security equipment. Attackers can read or change the database behind Fortinet FortiClient EMS 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 Apr 2026.[1]
Fortinet FortiClient EMS 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 an SQL injection in Fortinet FortiClient EMS. In its words: “Fortinet FortiClient EMS contains a SQL injection vulnerability that may allow an unauthenticated attacker to execute unauthorized code or commands via specifically crafted HTTP requests.”[1]
The CVE record adds: “An improper neutralization of special elements used in an sql command ('sql injection') vulnerability in Fortinet FortiClientEMS 7.4.4 may allow an unauthenticated attacker to execute unauthorized code or commands via specifically crafted HTTP requests.”[2]
The underlying weakness is SQL injection (CWE-89), 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 the organisation that published the CVE 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 FortiClient EMS.
Most families won’t have Fortinet FortiClient EMS; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 13 Apr 2026, 66 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 16 Apr 2026 to fix it.[1]
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 98%. 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, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[1]
- Check whether you use it.Fortinet FortiClient EMS 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 16 Apr 2026 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.[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 98%.[4] |
See also
Other Fortinet FortiClient EMS flaws
- CVE-2026-35616: improper access control ·
- CVE-2023-48788: SQL injection ·
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-2025-68686, Fortinet FortiOS: exposure of sensitive information to an unauthorized actor ·
- CVE-2026-39808, Fortinet FortiSandbox: OS command injection ·
Other SQL injection flaws
- CVE-2026-114625, Arista VeloCloud Orchestrator: SQL injection ·
- CVE-2026-76461, Cisco Secure Email Gateway: SQL injection ·
- CVE-2026-9586, Sangoma Switchvox: SQL injection ·
- CVE-2026-72898, Metabase: SQL injection ·
- CVE-2026-60137, WordPress Core: SQL injection ·
Added the same day
- CVE-2026-34621, Adobe Acrobat and Reader: prototype pollution ·
- CVE-2025-60710, Microsoft Windows: link following ·
- CVE-2023-36424, Microsoft Windows: out-of-bounds read ·
- CVE-2023-21529, Microsoft Exchange Server: deserialization of untrusted data ·
- CVE-2020-9715, Adobe Acrobat: use-after-free ·
Every Fortinet flaw on CISA’s list · Everything added in April 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “Fortinet FortiClient EMS SQL Injection Vulnerability”. Known Exploited Vulnerabilities Catalog, added 13 Apr 2026.
- ^ National Institute of Standards and Technology. “CVE-2026-21643 Detail”. National Vulnerability Database, published 6 Feb 2026.
- ^ Fortinet. Advisories and fixes: fortiguard.fortinet.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.977, percentile 99.9, 31 Oct 2026.
- CVE Program. “CVE-2026-21643”. 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.