CVE-2023-49554 in YASM
Summary
by MITRE • 01/03/2024
Use After Free vulnerability in YASM 1.3.0.86.g9def allows a remote attacker to cause a denial of service via the do_directive function in the modules/preprocs/nasm/nasm-pp.c component.
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Analysis
by VulDB Data Team • 06/18/2025
The CVE-2023-49554 vulnerability represents a critical use after free condition within the YASM assembler version 1.3.0.86.g9def, specifically manifesting in the do_directive function located within modules/preprocs/nasm/nasm-pp.c. This flaw constitutes a memory safety issue that can be exploited remotely to trigger denial of service conditions, making it particularly dangerous in environments where YASM is used for automated code processing or compilation workflows. The vulnerability arises from improper memory management practices where freed memory blocks are still referenced or accessed, creating potential points of system instability and crash conditions.
The technical implementation of this vulnerability stems from the improper handling of memory allocations within the directive processing function of the NASM preprocessor module. When the do_directive function processes certain input parameters, it may allocate memory for processing directives and subsequently free that memory without proper nullification of pointers. Attackers can craft malicious input that triggers this specific code path, causing the application to reference freed memory locations during subsequent operations. This use after free condition falls under the CWE-416 vulnerability classification, which specifically addresses the use of freed memory in software applications. The flaw is particularly concerning because it occurs within a preprocessing component that handles directive parsing, suggesting that even seemingly benign assembly code could trigger this condition when processed through YASM.
The operational impact of CVE-2023-49554 extends beyond simple denial of service scenarios, as it can potentially be leveraged for more sophisticated attacks within environments where YASM is integrated into automated build systems or continuous integration pipelines. Remote exploitation allows attackers to disrupt legitimate compilation processes, potentially causing cascading failures in software development workflows. In enterprise environments where YASM is used for assembling code as part of security tooling or embedded system development, this vulnerability could lead to extended service interruptions and compromise the integrity of software builds. The vulnerability's remote exploitability means that attackers do not require local system access, making it particularly dangerous in networked environments where YASM might be exposed to untrusted input streams.
Mitigation strategies for CVE-2023-49554 should prioritize immediate patching of affected YASM versions, with organizations monitoring for updated releases from the maintainers that address the memory management issues in the do_directive function. System administrators should implement input validation measures that prevent malformed directives from reaching the vulnerable code paths, particularly when YASM processes external or untrusted assembly files. The implementation of memory safety techniques such as address sanitization and heap verification tools can help detect similar issues in other components of the software stack. From an ATT&CK framework perspective, this vulnerability aligns with techniques related to privilege escalation and denial of service, as it can be used to disrupt system availability and potentially create opportunities for further exploitation within compromised environments. Organizations should also consider implementing network segmentation and access controls to limit exposure of systems running vulnerable versions of YASM, particularly in automated build and compilation environments where the attack surface is most significant.