CVE-2025-8843 is a heap-based buffer overflow vulnerability identified in the Netwide Assembler (NASM) version 2.17rc0, specifically within the macho_no_dead_strip function located in the outmacho.c source file. NASM is a widely used assembler for the x86 architecture, commonly employed in software development and reverse engineering tasks. The vulnerability arises due to improper handling of memory buffers on the heap, which can be manipulated by an attacker with local access to cause a buffer overflow condition. This overflow can potentially lead to memory corruption, allowing an attacker to execute arbitrary code, crash the assembler process, or cause denial of service. The attack vector requires local access with low privileges (PR:L), no user interaction, and no elevated authentication, making it feasible for local users or processes with limited permissions to exploit. The CVSS 4.0 base score is 4.8, indicating a medium severity level, reflecting limited impact due to the local access requirement and the complexity of exploitation. The vulnerability affects only the 2.17rc0 release candidate version of NASM, which may limit exposure to environments running this specific version. No public exploits are currently known in the wild, but the exploit details have been disclosed publicly, increasing the risk of future exploitation. No patches or fixes have been linked yet, so users of the affected version should consider mitigation strategies or upgrading to unaffected versions once available.

For European organizations, the impact of CVE-2025-8843 depends largely on the deployment of NASM 2.17rc0 within their development, build, or reverse engineering environments. Since NASM is primarily a development tool, the direct impact on production systems is limited; however, exploitation could allow a local attacker to escalate privileges or execute arbitrary code on developer machines or build servers. This could lead to compromise of source code integrity, insertion of malicious code during assembly, or disruption of software build pipelines. Organizations involved in software development, embedded systems, or security research are more likely to be affected. The medium severity rating and local access requirement reduce the risk for most enterprises, but insider threats or compromised internal accounts could leverage this vulnerability. Additionally, if build environments are shared or exposed via remote desktop or similar services, the attack surface increases. The confidentiality, integrity, and availability of software development assets could be impacted, potentially leading to intellectual property theft or supply chain compromise. European organizations with stringent software supply chain security requirements should prioritize addressing this vulnerability to maintain trust and compliance.

1. Upgrade NASM: Immediately upgrade to a NASM version later than 2.17rc0 once a patched release is available. Monitor official NASM channels for security updates. 2. Restrict Local Access: Limit local access to systems running NASM to trusted users only. Implement strict access controls and monitor for unauthorized local logins. 3. Use Sandboxing: Run NASM processes within sandboxed or containerized environments to contain potential exploitation impact. 4. Monitor Build Systems: Implement integrity checks and monitoring on build environments to detect anomalous behavior or unexpected process crashes. 5. Avoid Using Release Candidates in Production: Since 2.17rc0 is a release candidate, avoid deploying it in production or critical environments. 6. Apply Principle of Least Privilege: Ensure NASM runs with the minimum necessary privileges to reduce the impact of exploitation. 7. Incident Response Preparedness: Prepare for potential exploitation by having incident response plans that include detection of local privilege escalations and memory corruption exploits. 8. Code Review and Static Analysis: Incorporate static analysis tools to detect similar memory handling issues in custom assembler code or related tools.