CVE-2026-38754 in Busybox
Summary
by MITRE • 07/16/2026
A heap overflow in the ifsbreakup() function (shell/ash.c) of Busybox v1.38.0 allows attackers to cause a Denial of Service (DoS) via supplying a crafted input.
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Analysis
by VulDB Data Team • 07/16/2026
The vulnerability under discussion represents a critical heap buffer overflow condition within the busybox implementation, specifically within the ifsbreakup() function located in shell/ash.c file of version 1.38.0. This flaw manifests as a denial of service condition that can be triggered by maliciously crafted input sequences, potentially leading to system instability or complete service disruption. The vulnerability stems from insufficient bounds checking during string processing operations within the shell's parsing logic, where the function fails to properly validate input length before performing memory allocation and data copying operations.
The technical implementation of this heap overflow occurs when the ifsbreakup() function processes command line arguments or environment variables that exceed expected buffer boundaries. This function is responsible for breaking apart input strings based on field separators, and in the process of handling these operations, it allocates heap memory without adequate verification of input parameters. When an attacker supplies input that exceeds predetermined limits, the insufficient boundary checks cause data to be written beyond allocated memory regions, resulting in heap corruption that can trigger program termination or unpredictable behavior. The vulnerability aligns with CWE-121, which specifically addresses stack buffer overflow conditions, though this manifests in heap memory management within the shell implementation.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to potentially enable more sophisticated attack vectors when combined with other weaknesses within the busybox framework. Systems utilizing vulnerable busybox versions may experience complete shell session termination, application crashes, or even potential privilege escalation if the heap corruption affects critical system components. The vulnerability's exploitation requires minimal privileges and can be executed through standard user input mechanisms, making it particularly dangerous in environments where busybox is used for system administration tasks or embedded systems where shell functionality is integral to operations.
Mitigation strategies should focus on immediate patching of the vulnerable busybox version to the latest stable release that contains the heap overflow fix. Additionally, implementing input validation and sanitization measures at the application level can provide additional protection layers against such vulnerabilities. System administrators should also consider deploying runtime protections such as address space layout randomization and stack canaries where available. The vulnerability demonstrates the importance of rigorous input validation and memory management practices in shell implementations, aligning with ATT&CK technique T1059.004 for command and scripting interpreter usage. Organizations should perform comprehensive vulnerability assessments to identify all instances of vulnerable busybox installations and ensure proper security monitoring is in place to detect potential exploitation attempts.