Integer Overflow Vulnerability in FortiWeb Could Enable Denial of Service Attacks
Fortinet disclosed an integer overflow vulnerability in FortiWeb that could allow privileged authenticated attackers to cause denial of service via crafted HTTP requests.
Fortinet has disclosed an integer overflow vulnerability (CWE-190) in its FortiWeb web application firewall that could allow a privileged authenticated attacker to cause a denial of service condition. The vulnerability, tracked as FG-IR-26-108, affects multiple versions of FortiWeb and carries a CVSSv3 score of 4.4. No CVE identifier has been assigned yet.
The flaw resides in the administrative interface of FortiWeb and can be triggered by sending specially crafted HTTP requests. An attacker with administrative privileges could exploit this integer overflow to crash the system, disrupting web application security services. The vulnerability was reported by Jason McFadyen of TrendAI Research under a responsible disclosure program.
Affected versions include FortiWeb 8.0.0 through 8.0.3, FortiWeb 7.6.0 through 7.6.6, and all versions of FortiWeb 7.4, 7.2, and 7.0. Fortinet has released patches for the supported branches: upgrading to FortiWeb 8.0.4 or above, or FortiWeb 7.6.7 or above resolves the issue. For older versions (7.4, 7.2, 7.0), Fortinet recommends migrating to a fixed release.
While the vulnerability requires authenticated access, it poses a risk in environments where administrative accounts may be compromised or where multi-tenant deployments share the same appliance. A denial of service could render the FortiWeb appliance unavailable, potentially exposing backend web servers to attacks.
Fortinet has not reported any active exploitation of this vulnerability in the wild. However, given the critical role of FortiWeb in securing web applications, administrators are urged to apply patches promptly. The advisory was published on April 14, 2026.
This disclosure is part of a broader pattern of vulnerabilities in network security appliances, where administrative interfaces often become attack surfaces. Organizations should ensure that administrative access is tightly controlled and that multi-factor authentication is enforced.