CVE-2026-26157 in BusyBox
Summary
by MITRE • 02/11/2026
A flaw was found in BusyBox. Incomplete path sanitization in its archive extraction utilities allows an attacker to craft malicious archives that when extracted, and under specific conditions, may write to files outside the intended directory. This can lead to arbitrary file overwrite, potentially enabling code execution through the modification of sensitive system files.
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Analysis
by VulDB Data Team • 05/06/2026
The vulnerability identified as CVE-2026-26157 resides within BusyBox, a widely deployed collection of common Unix utilities that forms the foundation of numerous embedded systems and lightweight Linux environments. This flaw specifically targets the archive extraction functionality of BusyBox, which is commonly used for unpacking tar and other compressed archives across various network appliances, routers, and embedded devices. The issue stems from insufficient validation of file paths during the extraction process, creating a path traversal condition that can be exploited by malicious actors.
The technical implementation of this vulnerability involves incomplete path sanitization within BusyBox's archive handling code. When processing archive files, the system fails to adequately validate or normalize file paths before writing extracted content to disk. This deficiency allows attackers to craft specially designed archive files containing entries with path traversal sequences such as ../ or ..\ that bypass normal directory boundaries. The vulnerability manifests when the archive extraction process encounters these malformed paths without proper sanitization, resulting in files being written to locations outside the intended extraction directory.
The operational impact of CVE-2026-26157 extends significantly across various attack vectors and system configurations. The vulnerability can be exploited in scenarios where users or systems automatically extract untrusted archives, such as during software updates, package installations, or automated deployment processes. When successfully exploited, the flaw enables arbitrary file overwrites, potentially allowing attackers to modify critical system files, configuration files, or binary executables. This capability can lead to privilege escalation, persistent backdoors, or complete system compromise depending on the target environment and the privileges of the extraction process.
The vulnerability aligns with CWE-22 Path Traversal and CWE-77 Path Traversal in Unix/Linux environments, which are fundamental security weaknesses in file system operations. From an adversarial perspective, this vulnerability maps to ATT&CK technique T1059 Command and Scripting Interpreter and T1566 Phishing with Social Engineering, as attackers can leverage this flaw to deliver malicious payloads through compromised archives. The attack surface is particularly concerning in embedded systems where BusyBox is prevalent, including IoT devices, network infrastructure equipment, and containerized environments where automatic archive extraction is common. Organizations should prioritize immediate patching of affected systems and implement strict archive validation policies, including mandatory path sanitization and extraction to isolated directories, to prevent exploitation of this vulnerability across their infrastructure.