CVE-2024-42040 in U-Boot
Summary
by MITRE • 08/23/2024
Buffer Overflow vulnerability in the net/bootp.c in DENEX U-Boot from its initial commit in 2002 (3861aa5) up to today on any platform allows an attacker on the local network to leak memory from four up to 32 bytes of memory stored behind the packet to the network depending on the later use of DHCP-provided parameters via crafted DHCP responses.
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Analysis
by VulDB Data Team • 04/04/2026
The buffer overflow vulnerability identified as CVE-2024-42040 resides within the net/bootp.c component of DENEX U-Boot, a widely used embedded boot firmware that has been part of the software landscape since 2002. This vulnerability represents a critical security flaw that has persisted for over two decades, affecting all platforms where this firmware is implemented. The issue stems from improper input validation and memory handling within the BOOTP (Bootstrap Protocol) implementation that processes DHCP responses from network servers. The vulnerability specifically manifests when the system receives crafted DHCP responses that trigger an overflow condition in the packet processing buffer.
The technical flaw occurs in the way the bootp.c module handles incoming DHCP packets, particularly when processing options and parameters provided by DHCP servers. The buffer overflow allows an attacker positioned on the local network to manipulate the memory layout by injecting specially crafted DHCP responses that exceed the allocated buffer boundaries. This memory leakage exposes four to thirty-two bytes of memory that exists behind the packet buffer, potentially revealing sensitive information such as stack contents, heap data, or other critical system parameters. The vulnerability's impact is amplified by the fact that the attacker only requires network access to the local segment, making it particularly dangerous in environments where network segmentation is not properly enforced.
The operational impact of this vulnerability extends beyond simple information disclosure, as the leaked memory could contain cryptographic keys, session tokens, or other sensitive data that could be leveraged for further attacks. The exposure of memory contents creates opportunities for attackers to perform advanced persistent threats by analyzing the leaked data to understand system memory layout, identifying potential attack vectors, or extracting credentials that could be used to compromise the system. This vulnerability particularly affects embedded systems that rely on U-Boot for initial system boot and network configuration, including routers, network appliances, IoT devices, and industrial control systems where network access is typically untrusted.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security posture improvements. The primary solution involves updating to a patched version of DENEX U-Boot that properly validates buffer boundaries and implements secure memory handling practices. Organizations should also implement network segmentation to isolate systems running vulnerable U-Boot versions and deploy network monitoring to detect anomalous DHCP traffic patterns that might indicate exploitation attempts. Additionally, the implementation of DHCP snooping and other network security controls can help prevent unauthorized DHCP servers from operating on the network. This vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and maps to ATT&CK technique T1059.007 for execution via network protocols, highlighting the need for comprehensive network security controls to prevent exploitation. The persistence of this vulnerability across multiple years demonstrates the importance of regular security assessments and firmware updates in embedded systems environments where security patches may not be regularly applied.