CVE-2026-39808 — Fortisandbox
CRITICALCVE-2026-39808 is a critical-severity (CVSS 9.8) OS Command Injection vulnerability in fortinet fortisandbox. It is in CISA's Known Exploited Vulnerabilities catalog (added 2026-07-16) — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.
A improper neutralization of special elements used in an os command ('os command injection') vulnerability in Fortinet FortiSandbox 4.4.0 through 4.4.8 may allow attacker to execute…
Exploitation Status
Actively exploited in the wild
- Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2026-07-16. Federal agencies were required to remediate by 2026-07-19.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2026-39808.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-39808 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 384,189 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Counts from FIRST.org, log-scaled.
Description
A improper neutralization of special elements used in an os command ('os command injection') vulnerability in Fortinet FortiSandbox 4.4.0 through 4.4.8 may allow attacker to execute unauthorized code or commands via <insert attack vector here>
Affected Products
fortisandboxfortinetfortisandboxpaasfortinetResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Vendor / applianceDetect
Inventory every fortinet fortisandbox deployment and check each version against the affected-products list above.
Remediation status
No patch has shipped for CVE-2026-39808 yet — track the fortinet fortisandbox advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.
How to detect CVE-2026-39808
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2026-39808 -u https://target- Template
- Fortinet FortiSandbox - Command Injection
- Severity
- critical
- Impact
- Attackers can execute arbitrary code or commands, potentially leading to full system compromise.
- Remediation
- Upgrade FortiSandbox to version 4.4.9 or later.
Template by ProjectDiscovery nuclei-templates (DhiyaneshDk), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2026-39808 being exploited in your environment?
Detect and block the exploit chain at execution, on systems you cannot patch yet.