CVE-2023-47536 is an improper access control vulnerability identified in multiple versions of Fortinet's FortiOS and FortiProxy products. Specifically, affected versions include FortiOS 7.2.0, 7.0.13 and below, 6.4.14 and below, and FortiProxy 7.2.3 and below, 7.0.9 and below, and 2.0.12 and below. The vulnerability arises from a flaw in the enforcement of firewall deny policies based on geolocation (GeoIP). An attacker can exploit this by timing their network traffic to coincide with the update of the GeoIP database used by the firewall. During this update window, the firewall's deny geolocation policy can be bypassed, allowing remote unauthenticated attackers to access resources that should have been blocked based on geographic restrictions. The vulnerability is classified under CWE-284 (Improper Access Control), indicating that the system fails to enforce correct access restrictions. The CVSS v3.1 base score is 2.8, indicating a low severity level. The vector indicates that the attack can be performed remotely without privileges (AV:N/PR:N), but requires user interaction (UI:R) and has high attack complexity (AC:H). The impact is limited to a low integrity impact (I:L) with no confidentiality or availability impact. There are no known exploits in the wild at the time of publication. The vulnerability is particularly relevant for organizations relying on Fortinet's geolocation-based firewall policies to restrict access from certain countries or regions. The timing-based bypass suggests that attackers must carefully synchronize their attempts with GeoIP database updates, which may limit exploitability but still poses a risk to network segmentation and access control strategies.

For European organizations, this vulnerability could undermine geolocation-based access controls designed to block traffic from high-risk or non-European countries, potentially allowing unauthorized access during GeoIP database updates. This may expose sensitive internal resources or management interfaces to attackers who would otherwise be blocked. While the overall impact is rated low, the integrity of firewall policies is compromised, which could facilitate further reconnaissance or lateral movement if combined with other vulnerabilities or misconfigurations. Organizations using Fortinet products extensively for perimeter defense, especially those enforcing strict geolocation restrictions to comply with regulatory or internal policies, may find their defenses temporarily weakened. This could be exploited by threat actors targeting European entities, particularly in sectors like finance, government, or critical infrastructure, where geolocation filtering is part of a layered security approach.

1. Immediate application of vendor-provided patches or updates once available is critical to fully remediate the vulnerability. 2. Until patches are applied, organizations should monitor GeoIP database update schedules and consider temporarily disabling automatic updates during critical operational periods or implementing additional network monitoring during update windows. 3. Employ complementary access control mechanisms beyond geolocation filtering, such as IP reputation services, multi-factor authentication, and strict network segmentation, to reduce reliance on GeoIP-based policies alone. 4. Increase logging and alerting on firewall policy bypass attempts, especially during GeoIP update intervals, to detect potential exploitation attempts. 5. Conduct regular security assessments and penetration tests to verify that geolocation policies are enforced correctly and that no timing-based bypasses are possible. 6. Coordinate with Fortinet support for guidance on best practices for GeoIP database management and update procedures to minimize exposure.