CVE-2025-53379 in FortiAuthenticator
Summary
by MITRE • 07/14/2026
A out-of-bounds read vulnerability in Fortinet FortiAuthenticator 6.6.0 through 6.6.2, FortiAuthenticator 6.5 all versions may allow a remote unauthenticated attacker to retrieve sensitive information via a specially crafted request.
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Analysis
by VulDB Data Team • 07/14/2026
This vulnerability represents a critical out-of-bounds read flaw that affects multiple versions of Fortinet FortiAuthenticator authentication appliances. The issue stems from insufficient input validation within the application's request processing logic, where malicious actors can craft specially formatted HTTP requests that trigger memory access violations. Such vulnerabilities typically arise when software fails to properly bounds-check array indices or buffer operations before accessing memory locations, creating opportunities for unauthorized data disclosure.
The technical implementation of this flaw allows remote attackers to exploit the authentication service without requiring any credentials or prior access privileges. When processing malformed requests, the FortiAuthenticator software attempts to read data from memory locations beyond the intended buffer boundaries, potentially exposing sensitive information including system configuration details, user credentials, or internal application state. This type of vulnerability falls under the CWE-129 category of Improper Validation of Array Index and is classified as a remote information disclosure issue that can be leveraged by attackers positioned outside the network perimeter.
The operational impact of this vulnerability extends beyond simple information leakage, as the exposed data could provide attackers with critical insights into the authentication infrastructure. An attacker who successfully exploits this vulnerability gains access to sensitive system information that could aid in planning further attacks against the organization's authentication ecosystem. The vulnerability affects FortiAuthenticator versions 6.6.0 through 6.6.2 and all previous 6.5 releases, indicating a widespread exposure across multiple product generations within the Fortinet authentication portfolio.
Organizations utilizing affected FortiAuthenticator appliances should immediately implement mitigation strategies including applying the latest security patches from Fortinet, implementing network segmentation to limit access to authentication services, and monitoring network traffic for suspicious request patterns that may indicate exploitation attempts. The vulnerability's classification under ATT&CK technique T1083 (File and Directory Discovery) and T1566 (Phishing) suggests that attackers may use the leaked information to enhance social engineering campaigns or conduct more sophisticated reconnaissance activities against the affected environment. Additionally, security teams should consider implementing intrusion detection systems capable of identifying malformed requests that target this specific memory access pattern.
Fortinet has addressed this vulnerability through security updates that include enhanced input validation mechanisms and improved bounds-checking procedures within the authentication service processing pipeline. The remediation approach focuses on strengthening the application's defensive measures against malformed input while maintaining functionality of legitimate authentication operations. Organizations should also conduct thorough vulnerability assessments to identify any potential secondary impacts from information disclosure, as the exposed data could reveal system configurations that might be leveraged in combination with other vulnerabilities present within the network infrastructure.