CVE-2026-88835 in BusyBox
Summary
by MITRE • 09/23/2026
BusyBox dpkg read_package_field() steps past a NUL terminator on malformed .deb packages, causing an out-of-bounds heap read.
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Analysis
by VulDB Data Team • 09/23/2026
The vulnerability identified in BusyBox involves a critical memory safety flaw within the dpkg utility's package management functionality, specifically located in the read_package_field function. This component is responsible for parsing metadata from Debian software package files, commonly known as .deb packages. These archives contain control information that dictates how software should be installed and configured on systems utilizing the Debian packaging system. The core technical issue arises when the parser processes malformed or maliciously crafted .deb files where field terminators are improperly formatted. Specifically, the function fails to correctly handle NUL bytes that serve as string delimiters in C-based data structures. Instead of stopping at the first valid NUL terminator indicating the end of a metadata field, the logic steps past this boundary, leading to an out-of-bounds heap read operation.
This memory corruption issue classifies under CWE-125, which describes Out-of-Bounds Read vulnerabilities. In such scenarios, software reads data from a buffer beyond its allocated boundaries without proper validation or bounds checking. The consequence of stepping past the NUL terminator is that the application attempts to access memory locations that do not belong to the intended packet metadata structure. This can result in the leakage of sensitive information stored in adjacent heap memory regions, potentially exposing internal system states, cryptographic keys, or other private data belonging to the process. Furthermore, depending on the specific compiler optimizations and runtime environment, such an out-of-bounds read may trigger segmentation faults leading to denial of service conditions for the package management tool.
From a threat actor perspective, this vulnerability aligns with ATT&CK technique T1005, which refers to Data from Local System. An attacker could exploit this flaw by distributing specially crafted .deb packages through compromised repositories or phishing campaigns targeting system administrators who manually install software. By tricking the dpkg utility into processing these malformed archives during routine installation procedures, an adversary can extract sensitive heap contents that might aid in further exploitation stages such as information disclosure or lateral movement within a networked environment. The risk is particularly acute for embedded systems and IoT devices where BusyBox is frequently deployed due to its lightweight nature and comprehensive suite of Unix utilities.
Mitigation strategies primarily involve updating the BusyBox installation on affected systems to include patches that enforce strict bounds checking during package parsing operations. Developers must ensure that string processing functions correctly identify and respect NUL terminators without advancing pointers beyond allocated memory segments. Additionally, system administrators should exercise caution when installing software from untrusted sources or repositories with poor security hygiene. Implementing integrity checks such as GPG signatures for .deb packages can help detect tampered files before they are processed by vulnerable components. Regular auditing of package management logs and monitoring for unexpected crashes in dpkg processes can also serve as early detection mechanisms for potential exploitation attempts targeting this memory safety flaw.