CVE-2026-120740 in hivex
Summary
by MITRE • 11/03/2026
A flaw was found in hivex. By supplying a specially crafted Windows registry hive file, an attacker can trigger an out-of-bounds memory read when hivex parses registry values containing malformed large data block lists. This issue can cause the application processing the registry file to crash, resulting in a Denial of Service (DoS).
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified within the hivex library represents a critical security flaw rooted in improper input validation and memory management practices during the parsing of Windows registry hive files. Hivex is a widely used utility for reading and writing Microsoft Windows Registry Hive files, often employed by system administrators and developers to manipulate or analyze registry data without booting into a full Windows environment. The core technical issue arises when the application processes registry values that contain malformed large data block lists. Specifically, an attacker can construct a specially crafted hive file where the metadata describing these data blocks is inconsistent with the actual content or exceeds expected boundaries. When hivex attempts to parse this structure, it fails to correctly verify the bounds of the memory regions being accessed relative to the allocated buffer size. This oversight leads directly to an out-of-bounds read operation, a classic category of software defects where the program accesses memory locations that are not part of the intended data structure.
From a technical perspective, this flaw aligns with CWE-125, which defines Out-of-Bounds Read vulnerabilities. In such scenarios, the application reads beyond the allocated buffer boundaries, potentially accessing sensitive information from adjacent memory segments or causing undefined behavior depending on what resides in that unallocated space. While the immediate observable effect described is a crash leading to a Denial of Service, out-of-bounds reads can sometimes be leveraged for more severe impacts if the attacker has control over the data being read and how it influences subsequent program logic. However, in this specific instance, the primary consequence is stability failure rather than arbitrary code execution or information disclosure, as the malformed input triggers a fault that terminates the process to prevent further corruption of memory state.
The operational impact of this vulnerability is significant for any system relying on hivex to parse untrusted registry files. Since hive files can be generated by various tools and may originate from external sources such as malware samples or user-uploaded configurations, the attack surface is broad. An attacker who can persuade a victim to process a maliciously crafted hive file through an application utilizing hivex can cause that application to crash unexpectedly. This results in a Denial of Service condition, disrupting workflows that depend on continuous availability of registry analysis tools. In automated environments where such files are processed in bulk or as part of larger pipelines, this flaw could lead to service interruptions and require manual intervention to restart affected processes, thereby increasing operational overhead and reducing system reliability.
Mitigation strategies for this vulnerability primarily involve updating the hivex library to a patched version that includes rigorous bounds checking during the parsing phase. Developers integrating hivex into their applications should ensure they are using versions released after the fix was applied by upstream maintainers. Additionally, defensive programming practices such as implementing strict input validation before processing hive files can provide an additional layer of security. Security teams should also monitor for unusual crashes in systems running hivex and consider sandboxing or isolating processes that handle untrusted registry data to limit the blast radius of potential exploits. Awareness campaigns highlighting the risks associated with parsing unverified Windows registry structures are essential for maintaining robust system integrity against such memory safety violations.