CVE-2023-46805: Unpacking the FortiGate Authentication Bypass Vulnerability

CVE-2023-46805: Unpacking the FortiGate Authentication Bypass Vulnerability
TL;DR
CVE-2023-46805 is a critical authentication bypass vulnerability affecting Fortinet FortiGate SSL VPNs. Exploitation allows unauthenticated attackers to gain unauthorized access to the SSL VPN portal, potentially leading to further network compromise. This article delves into the technical nuances of the vulnerability, its impact, and defensive strategies.
Understanding CVE-2023-46805: The Technical Deep Dive
CVE-2023-46805, often discussed in conjunction with CVE-2023-27997, targets the web management interface of FortiGate devices. The core of the issue lies in how the system handles authentication requests, specifically concerning the validation of user credentials and session management.
The Vulnerability Mechanism:
At a high level, the vulnerability allows an attacker to craft specific HTTP requests that bypass the normal authentication checks. This bypass is achieved by manipulating parameters within the request, leading the FortiGate to believe the user is already authenticated, or to grant access to sensitive resources without proper verification.
While specific exploit code is not provided here for educational purposes, the underlying principle often involves:
- Improper Input Validation: The web interface might not sufficiently sanitize or validate certain input fields when processing authentication-related requests.
- State Management Flaws: The system's internal state or session management might be susceptible to manipulation, allowing an attacker to inject or alter session tokens or authentication flags.
- Path Traversal/Access Control Issues: In some scenarios, the vulnerability might be linked to how the system handles requests for specific web resources, allowing access to authenticated-only pages through crafted URLs.
Example Scenario (Conceptual):
Imagine a simplified authentication flow where a request to /remote/fgt_lang with a lang= parameter is processed. An attacker might discover that by providing a specific value to the lang parameter, or by appending other parameters, they can trigger a path that bypasses the authentication check for subsequent requests, such as accessing /remote/sslvpn_webportal.
A hypothetical, non-exploitable request that might be part of an attack chain could look something like this:
GET /remote/fgt_lang?lang=/../../../..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%252e%252e%252f..%2
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## Source Query
- Query: cve-2023-46805
- Clicks: 1
- Impressions: 4
- Generated at: 2026-04-29T18:28:44.731Z