CVE-2022-43391 in NR7101
Summary
by MITRE • 01/11/2023
A buffer overflow vulnerability in the parameter of the CGI program in Zyxel NR7101 firmware prior to V1.15(ACCC.3)C0, which could allow an authenticated attacker to cause denial-of-service (DoS) conditions by sending a crafted HTTP request.
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Analysis
by VulDB Data Team • 02/25/2026
The buffer overflow vulnerability identified as CVE-2022-43391 resides within the Common Gateway Interface program of Zyxel NR7101 network infrastructure device. This flaw affects firmware versions prior to V1.15(ACCC.3)C0 and represents a critical security weakness that can be exploited by authenticated attackers to disrupt service availability. The vulnerability manifests specifically when the CGI program processes parameter inputs, creating an opportunity for malicious actors to manipulate system behavior through carefully crafted HTTP requests.
The technical implementation of this vulnerability stems from improper input validation within the CGI parameter handling mechanism. When an authenticated user submits a specially crafted HTTP request containing oversized parameter values, the system fails to properly bounds-check the input data before processing. This allows the buffer to be overwritten with malicious data, potentially leading to arbitrary code execution or system crash conditions. The vulnerability aligns with CWE-121, which describes buffer overflow conditions where insufficient bounds checking allows data to be written beyond the allocated buffer space. The flaw demonstrates characteristics of stack-based buffer overflow scenarios where parameter data exceeds the allocated memory boundaries, creating potential for system instability and denial-of-service conditions.
The operational impact of this vulnerability extends beyond simple service disruption to encompass potential system compromise and unauthorized access. An authenticated attacker with network access to the device can leverage this weakness to cause persistent denial-of-service conditions, effectively rendering the network infrastructure unavailable to legitimate users. The attack vector requires authentication, which reduces the attack surface but does not eliminate the risk entirely since compromised credentials could be used by malicious actors. This vulnerability directly impacts the availability component of the CIA security triad, as it can be exploited to deny legitimate users access to network services through controlled system disruption. The potential for persistent service degradation makes this particularly concerning for network infrastructure devices that require continuous operation.
Mitigation strategies for CVE-2022-43391 should prioritize immediate firmware updates to version V1.15(ACCC.3)C0 or later, which contain the necessary patches to address the buffer overflow condition. Network administrators should implement strict access controls and monitor for unauthorized authentication attempts that could indicate exploitation attempts. The vulnerability demonstrates characteristics aligned with ATT&CK technique T1499.004, which involves network denial-of-service attacks targeting infrastructure devices. Additional protective measures include implementing network segmentation to limit access to critical infrastructure, deploying intrusion detection systems to monitor for suspicious HTTP request patterns, and establishing robust credential management practices. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in network infrastructure devices, as this vulnerability type remains prevalent in embedded systems and network appliances. The remediation process should also include comprehensive testing of updated firmware to ensure that the patch does not introduce compatibility issues with existing network configurations.