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CriticalPublic exploit

Unauthenticated OS Command Injection in Fortinet FortiSIEM phMonitor

IdentifiersCVE-2025-25256CWE-78· Improper Neutralization of Special…

CVE-2025-25256 is a critical OS command injection vulnerability in Fortinet FortiSIEM. According to the provided content, the flaw affects FortiSIEM 7.3.0 through 7.3.1, 7.2.0 through 7.2.5, 7.1.0 through 7.1.7, 7.0.0 through 7.0.3, and versions before 6.7.9, with broader reporting also indicating exposure across older 6.x branches. Fortinet describes the issue as improper neutralization of special elements used in an OS command, allowing an unauthenticated attacker to execute unauthorized code or commands via crafted CLI requests. Multiple supporting items tie exploitation to the phMonitor service, which is exposed on TCP port 7900 and processes inter-role FortiSIEM messages. The vulnerability enables remote command execution without authentication against vulnerable on-premises FortiSIEM deployments.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows unauthenticated remote execution of OS commands on vulnerable FortiSIEM systems. The content characterizes the impact as remote code execution, potentially as the FortiSIEM system user, with follow-on risk of full appliance compromise depending on local privilege-escalation opportunities or chained weaknesses. Reported consequences include unauthorized code execution, compromise of Supervisor and Worker nodes, possible log tampering, credential theft, lateral movement, and ransomware enablement. The content also states practical exploit code exists and that exploitation was observed or reported in the wild in some reporting, increasing operational risk.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, restrict access to the FortiSIEM phMonitor service on TCP port 7900. Fortinet’s guidance in the provided content recommends limiting access to this port and placing FortiSIEM in a protected network segment behind a firewall with no direct public internet exposure. Additional defensive measures supported by the content include reviewing phMonitor-related logs where available and reducing exposure of vulnerable on-premises Supervisor and Worker nodes.

Remediation

Patch, then assume compromise.

Upgrade FortiSIEM to a fixed release in the affected branch. Based on the provided content, fixed versions for CVE-2025-25256 are reported as 7.3.2+ / 7.3.5+, 7.2.6+ / 7.2.7+, 7.1.8+ / 7.1.9+, 7.0.4+, and 6.7.10+, depending on the source cited in the content. For unsupported 6.7/7.0 or older branches, migrate to a supported fixed release. Because the supplied content contains some version inconsistencies across summaries, the authoritative remediation should be taken from Fortinet’s official advisory for this CVE and the applicable product branch.
PUBLIC EXPLOITS

Exploits

No valid public exploits. Mallory filtered out 1 candidate as fakes, detection scripts, or README-only repos.

VALID 0 / 1 TOTALView more in app

All candidate exploits were filtered out by Mallory's validation.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
FortinetFortisiemapplication

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What this page doesn’t show

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Exposure mapping

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Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware1

Malware families riding this exploit, with evidence and IOCs.

Detection signatures1

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity105

Community discussion across Reddit, Mastodon, and other social sources.