Fortinet FortiOS Buffer Overflow (CVE-2025-14982): Critical RCE Risk for Firewalls

A newly disclosed buffer overflow in FortiOS could allow remote code execution on Fortinet firewalls — with no authentication required.

Vulnerability Overview

Fortinet has issued an urgent advisory for CVE-2025-14982, a critical buffer overflow vulnerability affecting certain versions of FortiOS, the operating system powering FortiGate firewalls. The flaw exists in the SSL VPN component, allowing an attacker to send crafted requests that overflow memory buffers and execute arbitrary code.

Because the vulnerability can be triggered without authentication, it is exploitable directly from the internet if the SSL VPN service is exposed — making it a prime target for automated mass scanning and exploitation campaigns.

Attack Vectors & Potential Impact

If exploited successfully, attackers could:

• Gain full control of the firewall, modifying configurations and disabling protections.
• Establish a foothold in segmented networks for further compromise.
• Pivot into sensitive internal systems, bypassing perimeter defenses entirely.

The combination of critical severity and pre-authentication exploitability places this flaw in the same risk category as other infamous Fortinet bugs that have been weaponized within days of disclosure.

Mitigation & Patching Guidance

Fortinet recommends:

1. Upgrading immediately to the patched FortiOS versions.
2. Disabling SSL VPN access from untrusted networks until updates are applied.
3. Monitoring logs for suspicious VPN login attempts and anomalies.
4. Reviewing firewall rules to ensure least privilege on remote access.

ThreatGrid Takeaways

• The internet-facing nature of many FortiGate deployments makes rapid patching non-negotiable.
• Organizations should assume scanning is already happening and act before proof-of-concept exploits become public.
• Attack surface reduction — limiting direct external access — remains one of the best defenses.