Critical FortiSIEM Vulnerability (CVE-2025-25256) Under Active Exploitation: What You Need to Know

TL;DR

Fortinet has issued a warning about a critical OS command injection vulnerability (CVE-2025-25256) in its FortiSIEM product, which is actively being exploited by threat actors. The flaw, rated 9.8 on the CVSS scale, allows unauthenticated attackers to execute arbitrary code via crafted CLI requests. Affected versions include FortiSIEM 6.1 through 7.3.1, excluding FortiSIEM 7.4. Immediate action is required to mitigate risks.

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Critical FortiSIEM Vulnerability (CVE-2025-25256) Actively Exploited: Fortinet Issues Urgent Warning

Fortinet has alerted customers to a critical vulnerability, tracked as CVE-2025-25256, affecting its FortiSIEM product. The vulnerability, which carries a CVSS score of 9.8, is classified as an OS command injection flaw and is actively being exploited in the wild. According to Fortinet, the flaw allows unauthenticated attackers to execute arbitrary code or commands on vulnerable systems through crafted CLI requests.

What Is CVE-2025-25256?

CVE-2025-25256 is an improper neutralization of special elements used in an OS command (‘OS Command Injection’) vulnerability (CWE-78). This type of vulnerability occurs when an application fails to properly sanitize user input, enabling attackers to inject malicious commands into the system.

Fortinet’s advisory confirms that practical exploit code for this vulnerability has been discovered in the wild, though no specific Indicators of Compromise (IoCs) have been provided¹.

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Affected Versions of FortiSIEM

The vulnerability impacts a wide range of FortiSIEM versions. Organizations using the following versions are urged to take immediate action:

• FortiSIEM 6.1, 6.2, 6.3, 6.4, 6.5, 6.6: Users must migrate to a fixed release.
• FortiSIEM 6.7.0 through 6.7.9: Upgrade to 6.7.10 or above.
• FortiSIEM 7.0.0 through 7.0.3: Upgrade to 7.0.4 or above.
• FortiSIEM 7.1.0 through 7.1.7: Upgrade to 7.1.8 or above.
• FortiSIEM 7.2.0 through 7.2.5: Upgrade to 7.2.6 or above.
• FortiSIEM 7.3.0 through 7.3.1: Upgrade to 7.3.2 or above.

FortiSIEM 7.4 is not affected by this vulnerability.

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Mitigation and Workarounds

Fortinet has recommended the following workarounds to mitigate the risk of exploitation while patches are being applied:

1. Limit Access to Port 7900: Restrict access to the phMonitor port (7900) to minimize exposure to potential attacks.

Organizations are strongly advised to upgrade to the latest patched versions as soon as possible to fully address the vulnerability.

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Why This Vulnerability Matters

OS command injection vulnerabilities, such as CVE-2025-25256, pose a severe risk to organizations. Successful exploitation can lead to:

• Unauthorized access to sensitive systems.
• Execution of malicious commands with elevated privileges.
• Compromise of critical infrastructure, leading to data breaches or operational disruptions.

Given the active exploitation of this vulnerability, organizations must prioritize patching and mitigation efforts to prevent potential cyberattacks.

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Conclusion

The discovery of CVE-2025-25256 underscores the importance of proactive vulnerability management in cybersecurity. Fortinet’s warning serves as a critical reminder for organizations to regularly update their systems and apply security patches promptly. Failure to address this vulnerability could result in severe security incidents, including data breaches and system compromises.

For the latest updates and guidance, refer to Fortinet’s official advisory¹ and ensure your systems are protected against this critical threat.

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Additional Resources

For further insights, check:

• Fortinet Advisory on CVE-2025-25256
• CWE-78: OS Command Injection

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References

1. Fortinet (2025). “FG-IR-25-152: FortiSIEM OS Command Injection Vulnerability”. FortiGuard. Retrieved 2025-08-13. ↩︎ ↩︎²