FortiClientEMS: Improper Certificate Validation
CVE-2026-59836 is a critical-severity improper certificate validation vulnerability in FortiClientEMS from Fortinet, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected FortiClientEMS versions: 7.4.3 through 7.4.5; 7.4.0 through 7.4.1; 7.2.12 through 7.2.14, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.22% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of FortiClientEMS you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on fortiguard.fortinet.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Fortinet | FortiClientEMS | 7.4.3 through 7.4.5; 7.4.0 through 7.4.1; 7.2.12 through 7.2.14; 7.2.0 through 7.2.10 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.5 | High | CNA (fortinet.com) |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
A improper certificate validation vulnerability in Fortinet FortiClientEMS 7.4.3 through 7.4.5, FortiClientEMS 7.4.0 through 7.4.1, FortiClientEMS 7.2 all versions may allow attacker to information disclosure via <insert attack vector here>
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Certificate Validation
The product does not validate, or incorrectly validates, a certificate.
How developers prevent this class of flaw
- Certificates should be carefully managed and checked to assure that data are encrypted with the intended owner's public key.
- If certificate pinning is being used, ensure that all relevant properties of the certificate are fully validated before the certificate is pinned, including the hostname.
More Improper Certificate Validation vulnerabilities (CWE-295)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in FortiClientEMS
- 9.8 Critical severity
- 9.8 Critical severity
Fortinet FortiClient EMS SQL Injection Exploited
- 7.2 High severity
- 9.8 Critical severity
- 7.3 High severity
- 8.1 High severity
Recent Improper Certificate Validation vulnerabilities
- 7.5 High severity
- 9.5 Critical severity
- 7.4 High severity
- 8.1 High severity
- 7.4 High severity
- 8.1 High severity
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