CVE-2021-32256 in Binutils
Summary
by MITRE • 07/18/2023
An issue was discovered in GNU libiberty, as distributed in GNU Binutils 2.36. It is a stack-overflow issue in demangle_type in rust-demangle.c.
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Analysis
by VulDB Data Team • 03/16/2026
The vulnerability identified as CVE-2021-32256 represents a critical stack overflow condition within GNU libiberty, a component distributed as part of GNU Binutils 2.36. This flaw specifically manifests within the demangle_type function located in the rust-demangle.c source file, which is responsible for processing and interpreting mangled symbol names during binary analysis operations. The issue arises when the demangler encounters certain malformed or specially crafted input data that triggers improper stack memory handling, potentially leading to arbitrary code execution or system instability. This vulnerability directly impacts the security posture of systems that rely on GNU Binutils for binary analysis, debugging, and reverse engineering activities, as the demangler functionality is commonly invoked during routine operations such as symbol resolution and debugging processes.
The technical implementation of this stack overflow stems from inadequate input validation and memory boundary checking within the rust-demangle.c implementation. When processing mangled Rust symbol names, the demangle_type function fails to properly validate the length and structure of input data before performing recursive parsing operations. This allows attackers to craft malicious input sequences that cause the function to exceed allocated stack buffer boundaries, leading to stack corruption and potential exploitation. The vulnerability operates at the application level within the GNU Binutils framework, making it particularly dangerous as it can be triggered through normal binary analysis workflows without requiring special privileges or conditions. According to CWE classification, this represents a CWE-121: Stack-based Buffer Overflow, which is characterized by insufficient bounds checking on stack-allocated buffers during program execution.
The operational impact of CVE-2021-32256 extends beyond simple system instability, as it can enable remote code execution when the affected demangler functionality is invoked with malicious input. Systems utilizing GNU Binutils for debugging, profiling, or binary analysis are particularly vulnerable, especially those that process untrusted binary data from external sources. Attackers could exploit this vulnerability by providing specially crafted binary files or symbol data that triggers the vulnerable demangle_type function during normal operation. The exploitation could lead to complete system compromise, data exfiltration, or denial of service conditions. This vulnerability aligns with ATT&CK technique T1059.007 for execution through Unix Shell commands and T1555.003 for credential access through system binary manipulation, as the compromised system could be used to execute further malicious activities or access sensitive information stored in memory.
Mitigation strategies for CVE-2021-32256 primarily focus on updating to patched versions of GNU Binutils where the stack overflow has been addressed through proper input validation and buffer boundary checking. System administrators should immediately upgrade to GNU Binutils 2.36.1 or later versions that contain the necessary patches to prevent the vulnerable demangle_type function from being exploited. Additionally, implementing input sanitization measures when processing binary data, particularly in environments where untrusted inputs are common, can provide defense-in-depth protection. Organizations should also consider implementing runtime monitoring and intrusion detection systems to identify potential exploitation attempts targeting this vulnerability. The patch implementation addresses the root cause by adding proper bounds checking and memory allocation validation within the rust-demangle.c file, preventing recursive parsing operations from exceeding stack buffer limits. Security teams should conduct comprehensive vulnerability assessments to identify all systems running affected versions of GNU Binutils and ensure complete remediation across their infrastructure to prevent potential exploitation attempts that could leverage this vulnerability for unauthorized system access.