CVE-2025-29864 is a vulnerability identified in ESTsoft ALZip, a popular file compression and archiving tool for Windows, specifically affecting versions from 12.01 up to but not including 12.29. The vulnerability is classified as a Protection Mechanism Failure (CWE-693), where the software fails to adequately enforce security controls designed to prevent malicious files from bypassing Windows SmartScreen, a security feature that warns users about unrecognized or potentially harmful applications. The flaw allows an attacker to craft or modify archive files in a way that circumvents SmartScreen's detection mechanisms, potentially enabling the execution of malicious payloads without triggering user warnings. According to the CVSS 4.0 vector, the attack requires local access (AV:L), low attack complexity (AC:L), no privileges (PR:N), and user interaction (UI:A). The vulnerability does not impact confidentiality, integrity, or availability directly but compromises the effectiveness of a critical security control, increasing the risk of malware infection. No known exploits have been reported in the wild, and no patches were listed at the time of publication, indicating that remediation may still be pending. The vulnerability was reserved in March 2025 and published in December 2025, suggesting a recent discovery. The high scope and security impact metrics (SC:H, SI:H, SA:H) indicate that the vulnerability affects multiple components or security domains within the system, amplifying its potential impact. This issue is particularly relevant for environments where ALZip is used to handle compressed files, as attackers could leverage this bypass to deliver malicious content more stealthily.

For European organizations, the primary impact of CVE-2025-29864 lies in the increased risk of malware infections due to the bypass of SmartScreen protections. Since SmartScreen is a widely used defense mechanism in Windows environments to prevent execution of untrusted applications, its circumvention can lead to higher chances of successful phishing, ransomware, or other malware attacks delivered via compressed archives. This can compromise the confidentiality and integrity of sensitive data, disrupt business operations, and increase incident response costs. Organizations relying on ALZip for file decompression or archival management may inadvertently expose users to malicious files without adequate warning. The vulnerability does not directly cause system compromise but lowers the barrier for attackers to trick users into executing harmful code. This is especially concerning for sectors with high regulatory requirements such as finance, healthcare, and critical infrastructure, where malware infections can have severe operational and compliance consequences. Additionally, the lack of available patches at the time of disclosure may delay mitigation efforts, prolonging exposure. The medium severity rating suggests that while the threat is not critical, it is significant enough to warrant prompt attention to avoid exploitation in targeted attacks or supply chain compromises.

1. Monitor ESTsoft communications and security advisories closely for the release of official patches or updates addressing CVE-2025-29864 and apply them immediately upon availability. 2. Until patches are available, consider restricting or auditing the use of ALZip within the organization, especially for handling files from untrusted sources. 3. Implement additional endpoint security controls such as advanced malware detection, behavior analysis, and application whitelisting to detect and block malicious payloads that might bypass SmartScreen. 4. Educate users about the risks of opening compressed files from unknown or suspicious origins, emphasizing caution even if SmartScreen warnings are absent. 5. Employ network-level protections like sandboxing and email filtering to intercept malicious archives before they reach end users. 6. Review and tighten local user permissions to limit the ability of attackers to execute or deliver malicious files requiring user interaction. 7. Use alternative compression tools with verified security postures as a temporary workaround if feasible. 8. Conduct regular security assessments and penetration testing focusing on file handling and endpoint defenses to identify potential exploitation paths related to this vulnerability.