CVE-2026-71407 in FortiPAM
Summary
by MITRE • 08/12/2026
A Stack-based Buffer Overflow vulnerability [CWE-121] vulnerability in Fortinet FortiOS 7.6.1 through 7.6.6 may allow an unauthenticated attacker who can bypass stack protection and ASLR to execute arbitrary code or commands in the context of the WAD daemon via crafted sockets, only if the explicit proxy is configured with Kerberos authentication and SOCKS enabled.
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Analysis
by VulDB Data Team • 08/12/2026
This vulnerability represents a critical stack-based buffer overflow flaw classified as CWE-121 that affects Fortinet FortiOS versions ranging from 7.6.1 through 7.6.6. The flaw specifically impacts the Web Application Firewall (WAD) daemon functionality when certain proxy configurations are active, creating a significant attack surface for unauthenticated remote code execution. The vulnerability requires specific preconditions to be exploitable, including the explicit proxy configuration with Kerberos authentication and SOCKS protocol enabled, which narrows the attack vector but does not eliminate its severity.
The technical mechanism of this vulnerability involves a classic stack-based buffer overflow condition where malicious input data exceeds the allocated buffer space within the WAD daemon process. This occurs when crafted socket connections are established through the explicitly configured proxy with Kerberos authentication and SOCKS protocols active. The attacker must first bypass modern exploit mitigations including stack canaries and address space layout randomization, which represents a significant operational challenge that limits the vulnerability's practical exploitation scope but does not eliminate it entirely.
The operational impact of this vulnerability extends beyond simple code execution to potentially compromise the entire FortiOS appliance when exploited successfully. Since the WAD daemon typically operates with elevated privileges within the system context, successful exploitation could provide attackers with complete control over the device's functionality, including access to network traffic inspection capabilities, proxy configurations, and potentially sensitive data passing through the firewall. This vulnerability directly aligns with ATT&CK technique T1059.007 for command and scripting interpreter and T1566.001 for credential access through valid accounts, as the attack path leverages legitimate authentication mechanisms while executing arbitrary code.
The exploitation complexity requires attackers to understand both the specific FortiOS configuration requirements and the underlying network protocols involved in the WAD daemon's operation. The requirement for explicit proxy with Kerberos authentication and SOCKS enabled configuration creates a controlled environment where this vulnerability becomes exploitable, though it also means that organizations without these specific configurations are not immediately at risk. However, the potential impact remains severe given that successful exploitation could lead to complete system compromise.
Organizations should prioritize immediate patching of affected FortiOS versions to address this vulnerability, as the window for exploitation exists while the system remains unpatched. Additionally, network segmentation and monitoring should be implemented to detect unusual socket connection patterns that might indicate attempted exploitation of this vulnerability. The mitigation strategy should include disabling unnecessary proxy configurations, particularly those involving Kerberos authentication and SOCKS protocols when not required, along with implementing robust network monitoring solutions that can detect anomalous traffic patterns consistent with buffer overflow exploitation attempts.
The vulnerability demonstrates how complex enterprise security appliances can contain subtle flaws in their daemon implementations that create significant security risks when specific configuration conditions are met. This particular weakness highlights the importance of thorough security testing of network appliance components and the need for comprehensive patch management processes to address vulnerabilities that may not be immediately obvious but can have severe operational consequences. Security teams should also consider implementing additional controls such as intrusion detection systems specifically configured to monitor for patterns consistent with buffer overflow exploitation attempts against known vulnerable services.