CVE-2026-118447 in pybddisasm
Summary
by MITRE • 11/03/2026
A use of uninitialized memory vulnerability in the pybddisasm Python bindings may disclose process memory when instruction decoding fails. The nd_decode, nd_decode_ex, nd_decode_ex2, and nd_decode_with_context functions may return an INSTRUX object whose contents have not been initialized after an unsuccessful decoding operation, including failures caused by invalid parameters. Accessing members of the returned object may expose residual process memory. Exploitation requires an application to access and expose the returned object contents after a decoding failure. The pybddisasm package is no longer maintained.
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified in the pybddisasm Python bindings represents a classic instance of improper initialization of resources, specifically categorized under CWE-908 as Use of Uninitialized Resource. This security flaw resides within the core instruction decoding functions, namely nd_decode, nd_decode_ex, nd_decode_ex2, and nd_decode_with_context. These functions are designed to parse binary machine code into structured INSTRUX objects that contain detailed information about the decoded instructions. However, under specific failure conditions, such as when invalid parameters are passed or when the input data cannot be successfully interpreted by the underlying disassembly engine, these functions fail to properly initialize the memory allocated for the returned object before returning it to the caller.
When a decoding operation fails, instead of raising an exception or returning a null reference that indicates failure, the function returns an INSTRUX object whose internal state contains residual data from previous allocations in the process heap. This behavior creates a direct information disclosure vector because any subsequent access to members of this returned object will read uninitialized memory contents rather than valid instruction metadata. The severity of this vulnerability lies in its potential to leak sensitive information residing in the application's address space, which may include cryptographic keys, session tokens, or other proprietary data that was previously stored and not securely wiped from memory after use.
Exploitation of this flaw requires a specific sequence of events where an attacker can influence the input parameters to trigger a decoding failure while simultaneously controlling how the resulting object is accessed within the Python application logic. If the calling code does not rigorously check for error conditions before accessing fields on the returned INSTRUX object, it will inadvertently expose these uninitialized memory regions. This aligns with ATT&CK technique T1083, File and Directory Discovery, or more broadly T1074, Data Staged, depending on how the leaked data is utilized by an attacker to further compromise the system. The impact extends beyond simple information leakage as it can facilitate subsequent attacks such as memory corruption exploits if the uninitialized values are used in conditional logic that affects control flow.
The operational impact of this vulnerability is significant for applications relying on pybddisasm for dynamic binary analysis, reverse engineering tasks, or security research tools. Since Python bindings often abstract low-level memory management, developers may assume that object instantiation guarantees a clean state unless explicitly stated otherwise. The failure to enforce strict initialization protocols in error paths violates the principle of least privilege and secure default states recommended by industry standards like OWASP Secure Coding Practices. Attackers can leverage this weakness to perform side-channel attacks or gather intelligence about the host environment, potentially leading to full system compromise if combined with other vulnerabilities such as buffer overflows that rely on predictable memory layouts.
Mitigation strategies for this vulnerability are primarily architectural and procedural due to the nature of the defect. The most effective remediation is to upgrade to a maintained alternative library or patch the specific bindings if updates become available, although it has been noted that the pybddisasm package is no longer actively maintained. For organizations still dependent on this toolset, implementing strict error handling patterns in Python code is critical. Developers must ensure that every call to nd_decode variants checks for failure states before accessing any attributes of the returned object. Additionally, integrating static analysis tools configured to detect CWE-908 violations can help identify similar uninitialized memory usage patterns across the codebase. In environments where this library remains in use, isolating the disassembly operations within sandboxed processes with restricted memory access permissions can limit the blast radius should an exploitation attempt succeed.