CVE-2025-53816 is a heap-based buffer overflow vulnerability identified in the ipavlov 7-Zip file archiver, specifically affecting versions prior to 25.0.0. The vulnerability arises in the RAR5 archive handler component, where zero bytes are written outside the allocated heap buffer boundaries. This improper memory handling can lead to memory corruption, which in turn may cause denial of service (DoS) conditions. The flaw is classified under CWE-122, indicating a classic heap-based buffer overflow issue. Exploitation does not require user interaction, authentication, or elevated privileges, but the attack vector is local (AV:L), meaning an attacker must have local access to the system to trigger the vulnerability. The CVSS v4.0 base score is 5.5 (medium severity), reflecting moderate impact primarily on availability due to potential crashes or service interruptions. No known exploits are currently reported in the wild, and the vendor has addressed the issue in version 25.0.0 of 7-Zip. The vulnerability does not affect confidentiality or integrity directly but can disrupt system stability and availability when processing maliciously crafted RAR5 archives.

For European organizations, the impact of CVE-2025-53816 centers on potential denial of service scenarios caused by processing malicious RAR5 archives with vulnerable 7-Zip versions. Given 7-Zip's widespread use across various sectors for file compression and decompression, including government, finance, healthcare, and manufacturing, an attacker with local access could cause application or system crashes, disrupting business operations. While the vulnerability does not allow remote exploitation or privilege escalation, insider threats or compromised local accounts could leverage this flaw to degrade service availability. This may affect critical workflows involving compressed data handling, automated archival processes, or forensic investigations. Additionally, organizations relying on automated unpacking of RAR5 archives in security tools or data pipelines may experience interruptions or failures. The absence of known exploits reduces immediate risk, but the medium severity rating and ease of triggering the flaw locally warrant prompt remediation to maintain operational continuity and security posture.

European organizations should prioritize upgrading all instances of 7-Zip to version 25.0.0 or later, where the vulnerability is patched. For environments where immediate upgrade is not feasible, implementing strict access controls to limit local user permissions can reduce the risk of exploitation. Monitoring and restricting the use of untrusted RAR5 archives, especially from external or unknown sources, is advisable. Incorporating file integrity monitoring and sandboxing techniques for archive processing can help detect and contain anomalous behavior triggered by malformed archives. Security teams should also review automated workflows that handle RAR5 files to ensure they include error handling and fail-safe mechanisms. Regular vulnerability scanning and asset inventory updates will help identify vulnerable 7-Zip installations. Finally, educating users about the risks of opening untrusted compressed files can further reduce exposure.