What happened
A critical FortiSIEM vulnerability lets attackers execute arbitrary OS commands over TCP because a flaw in Fortinet FortiSIEM’s phMonitor component improperly neutralizes special elements in command inputs, enabling unauthenticated remote execution via crafted TCP packets. The issue, tracked as CVE‑2025‑64155 with a CVSS score of 9.4, affects multiple releases of FortiSIEM and exposes both Supervisor and Worker nodes listening on port 7900 to exploitation without any authentication or user interaction, potentially resulting in full‑system compromise of core SIEM infrastructure. This vulnerability is critical to security operations environments as FortiSIEM aggregates logs, telemetry, and alerting, and unauthorized command execution could allow attackers to control or disrupt monitoring, evade detection, or pivot within enterprise networks.
Who is affected
Organizations running Fortinet FortiSIEM appliances, including large enterprises, governments, managed security providers, and SOC environments with network access to phMonitor services, face direct exposure to remote compromise if they have not applied updated patches.
Why CISOs should care
Because SIEM infrastructure is foundational to detection, alerting, and threat response, this flaw undermines core security visibility, increases attack surface, and could allow adversaries to disable monitoring, inject false alerts, or gain deeper access before detection.
3 practical actions
- Apply latest vendor updates: Patch affected FortiSIEM versions immediately to remediate the OS command injection flaw.
- Limit network exposure: Restrict access to the phMonitor service and block TCP port 7900 from untrusted networks.
- Monitor for abnormal activity: Watch for unauthorized CLI and system command executions in SIEM logs.