CVE-2026-25089

What it actually does

CVE-2026-25089 is an unauthenticated OS command injection vulnerability in Fortinet FortiSandbox, FortiSandbox Cloud, and FortiSandbox PaaS. A remotely reachable HTTP interface fails to properly neutralize shell metacharacters or command syntax in attacker-controlled input, allowing crafted HTTP requests to cause the appliance or service to execute arbitrary operating-system commands. Because exploitation requires network access only and no credentials or user interaction, successful exploitation can result in full compromise of confidentiality, integrity, and availability of the affected FortiSandbox instance, including command execution, malware staging, persistence, data access, configuration theft, and service disruption.

Why it matters to the business

This vulnerability can let an external attacker take control of a FortiSandbox system that is intended to analyze and contain suspicious files, turning a security control into an intrusion foothold. Compromise could expose submitted files, analysis results, credentials or integration tokens, and network connectivity used by the sandbox, while also allowing attackers to disable or manipulate malware analysis workflows. The CVSS score is critical, EPSS is high, exploitation is active in the wild, and the vulnerability is listed in CISA KEV with a remediation due date of 2026-07-19, so organizations should treat internet-exposed or broadly reachable deployments as urgent remediation targets. No ransomware use is indicated from the provided KEV context, but active exploitation against security infrastructure materially increases operational risk.

How an attack unfolds

An attacker first identifies a FortiSandbox, FortiSandbox Cloud, or FortiSandbox PaaS instance exposing the vulnerable HTTP interface. They then send a specially crafted HTTP request containing command separators, shell substitution syntax, or other OS command elements in a vulnerable parameter or request component. The application passes that input into an operating-system command without sufficient neutralization, causing the underlying system to execute attacker-supplied commands with the privileges of the vulnerable service. After confirming execution, the attacker may run discovery commands, retrieve configuration data, create or download payloads, establish reverse shells or outbound callbacks, tamper with analysis functions, and use credentials or integrations available to the appliance to move further into connected environments. Active in-the-wild exploitation means defenders should assume public exploit knowledge or reliable exploit tooling exists, even if specific exploit details are not provided here.

How to fix it

Upgrade affected Fortinet products to a vendor-fixed, supported release as soon as Fortinet makes the applicable fixed versions available for the deployed product line. The affected ranges are FortiSandbox 5.0.0 through 5.0.5, FortiSandbox 4.4.0 through 4.4.8, all FortiSandbox 4.2 versions, FortiSandbox Cloud 5.0.4 through 5.0.5, and FortiSandbox PaaS 5.0.4 through 5.0.5. If an immediate upgrade is not possible, restrict access to FortiSandbox HTTP management and service interfaces to trusted administrative networks only, remove direct internet exposure, enforce VPN or private access paths, apply firewall allowlists, disable unused interfaces and integrations, and monitor or block outbound command-and-control style traffic from the appliance. Because this is a command-injection issue with active exploitation, compensating controls should be considered temporary; patching or moving to a non-affected release is the primary remediation.

How to confirm the fix worked

Confirm the deployed product and version from the FortiSandbox administrative interface, CLI, or asset inventory and verify it is not within the affected ranges. Validate that FortiSandbox HTTP interfaces are not directly internet-exposed unless explicitly required and protected by strict access controls. Run authenticated vulnerability scans or vendor checks that identify CVE-2026-25089 exposure, and confirm scanner results after upgrade or mitigation. Review firewall and access-control policy to ensure only approved source networks can reach administrative or service endpoints. For cloud and PaaS deployments, verify the service has been updated or remediated according to Fortinet guidance and that no vulnerable 5.0.4-5.0.5 service instance remains. Avoid using intrusive exploit tests in production; if validation requires proof-of-fix testing, use vendor-approved checks or conduct controlled testing in an isolated environment.

Typical attack path

1. Scan for Fortinet FortiSandbox, FortiSandbox Cloud, or FortiSandbox PaaS HTTP interfaces exposed to the internet or reachable from compromised networks.
2. Fingerprint software version or behavior to determine whether it falls within FortiSandbox 5.0.0-5.0.5, 4.4.0-4.4.8, 4.2 all versions, FortiSandbox Cloud 5.0.4-5.0.5, or FortiSandbox PaaS 5.0.4-5.0.5.
3. Send a crafted unauthenticated HTTP request containing OS command syntax to the vulnerable interface.
4. Validate command execution using low-noise commands such as identity, hostname, network, or file-write checks.
5. Execute follow-on commands to enumerate the host, retrieve configuration or submitted analysis data, and identify credentials or connected services.
6. Stage tooling through curl, wget, shell scripts, or other native utilities if outbound network access is available.
7. Establish persistence, a reverse shell, scheduled task, or equivalent access mechanism where possible.
8. Use the compromised sandbox as a trusted security appliance foothold to pivot, exfiltrate data, or disrupt malware-analysis operations.

How to detect it

Investigate whether the FortiSandbox HTTP interface received unauthenticated requests containing shell metacharacters, command substitution, encoded command syntax, or attempts to invoke common utilities such as id, uname, whoami, curl, wget, sh, bash, chmod, nc, or busybox. Useful log sources include FortiSandbox system and event logs, web access logs if available, reverse proxy or load balancer logs, firewall logs, WAF logs, EDR telemetry on the appliance where available, DNS logs, NetFlow, outbound proxy logs, and authentication or configuration-change audit logs. Look for HTTP requests with suspicious characters in URI, query string, headers, or body, including semicolons, pipes, backticks, dollar-parentheses, URL-encoded shell syntax, newline injection, or command chaining. On host telemetry, look for the FortiSandbox web or application service spawning unexpected child processes such as /bin/sh, bash, wget, curl, nc, python, perl, chmod, or busybox. Network indicators include unusual outbound connections from the appliance to external IP addresses, newly observed DNS lookups, file downloads to temporary directories, reverse-shell style long-lived connections, or traffic to uncommon ports. File-system indicators include newly created executable files, scripts, web-accessible files, modified startup scripts, cron entries, or artifacts under temporary directories. Since exploitation is active in the wild and the affected product is security infrastructure, absence of a single known public IOC should not be treated as proof of no compromise; combine log review, process lineage, file integrity checks, and network egress analysis.

• /bin/sh
• sh -c
• /bin/bash
• bash -c
• bash -i
• /usr/bin/wget
• wget http
• wget https
• /usr/bin/curl
• curl http
• curl https
• chmod +x
• /tmp/
• /var/tmp/
• /dev/shm/
• busybox
• nc -e
• ncat -e
• python -c
• perl -e
• `id`
• $(id)
• ;id
• |id
• ;whoami
• |whoami
• ;uname -a
• |uname -a
• %3Bid
• %7Cid
• %24%28id%29
• %60id%60

What your security team should do

• Treat this as an emergency remediation item for any internet-exposed or broadly reachable FortiSandbox deployment because it is unauthenticated, critical severity, high EPSS, listed in CISA KEV, and actively exploited in the wild.
• Identify all FortiSandbox, FortiSandbox Cloud, and FortiSandbox PaaS deployments and map them to affected version ranges immediately.
• Upgrade to a vendor-fixed supported release or obtain Fortinet remediation guidance for the exact product line; if no fixed version is available for a deployment, isolate the service until remediation is possible.
• Remove direct internet exposure and restrict HTTP access to trusted administrative networks or private access paths only.
• Hunt for evidence of prior command execution, suspicious child processes, outbound callbacks, downloaded payloads, and unexpected file creation on or from FortiSandbox systems.
• Review FortiSandbox integrations, API tokens, credentials, file shares, and connected security tooling for possible exposure if compromise is suspected.
• Rotate credentials and integration secrets accessible to the appliance after patching if exploitation cannot be ruled out.
• Add SIEM detections for HTTP requests containing shell metacharacters and for security-appliance processes spawning shells, download utilities, or network tools.
• Prioritize completion before the CISA KEV due date of 2026-07-19 for covered environments and use that date as an internal deadline for all high-risk deployments.
• If exploitation indicators are found, preserve logs and disk artifacts, isolate the appliance, perform forensic triage, rebuild or reimage if necessary, and conduct broader lateral-movement investigation.