PoC exploit for critical FortiSIEM vulnerability released (CVE-2025-64155)

CVE-2025-25256 is a critical (CVSS 9.8) OS command injection flaw (CWE-78) in Fortinet's FortiSIEM SIEM platform. An unauthenticated attacker can trigger it by sending specially crafted CLI requests over the network, which the appliance fails to properly neutralize before execution. Successful exploitation allows the attacker to execute unauthorized code or commands on the affected system without credentials or user interaction, effectively giving control of the appliance. Essentially every currently supported and many older FortiSIEM releases are affected, spanning versions 4.7 through 7.3.1. Fortinet has confirmed exploit code is being used in the wild, and the flaw carries a high 60.3% EPSS probability of exploitation within 30 days, though it is not yet in CISA's KEV catalog.

Do: Upgrade FortiSIEM to a fixed release per Fortinet's security advisory, ensuring the deployed version falls outside all affected ranges listed above; given in-the-wild exploitation and a ~60% EPSS probability, prioritize externally reachable instances. Until patched, restrict network access to the appliance's CLI/management-facing services and review logs for unexpected commands or connections that may indicate compromise.

Fortinet FortiSIEM contains an unauthenticated OS command injection flaw (CWE-78) caused by improper neutralization of special elements used in an OS command. A remote attacker can trigger it by sending crafted TCP requests to the vulnerable service, requiring no credentials or user interaction. Successful exploitation allows execution of unauthorized code or commands on the SIEM host, giving an attacker control over a high-value security monitoring platform. Every current FortiSIEM release branch is affected: 7.4.0, 7.3.0 through 7.3.4, 7.1.0 through 7.1.8, 7.0.0 through 7.0.4, and 6.7.0 through 6.7.10. A public proof-of-concept exploit has been released, and EPSS assigns a 43.2% probability of exploitation within 30 days (99th percentile), though the flaw is not yet in CISA KEV and no confirmed in-the-wild exploitation has been reported.

Do: Upgrade FortiSIEM to the fixed release specified in Fortinet's advisory for CVE-2025-64155 as soon as possible, since exploitation requires only network reachability and no authentication. Until patched, restrict access to FortiSIEM's network-facing TCP services (management and event-ingestion interfaces) to trusted management networks and sources. Given the public proof-of-concept and high EPSS score, prioritize checking internet-exposed FortiSIEM instances for signs of exploitation and review logs for unexpected command execution.