CVE-2025-61728 identifies a vulnerability in the Go programming language's standard library, specifically within the archive/zip package. The root cause is an inefficient algorithm used for indexing file names inside ZIP archives, which operates with super-linear time complexity. This algorithm is invoked the first time a file within a ZIP archive is accessed. A malicious actor can craft a ZIP archive designed to exploit this inefficiency, causing the algorithm to consume excessive CPU cycles, leading to a denial of service (DoS) condition. The vulnerability affects all Go versions from the initial release up to and including version 1.25.0. The CVSS v3.1 base score is 6.5 (medium severity), reflecting that the attack vector is network-based (AV:N), requires no privileges (PR:N), but does require user interaction (UI:R) to open the malicious ZIP file. The impact is limited to availability, with no confidentiality or integrity compromise. No patches or fixes have been published yet, and no known exploits are currently active in the wild. This vulnerability is classified under CWE-407 (Inefficient Algorithmic Complexity), which highlights performance degradation risks due to algorithmic inefficiencies. The threat is particularly relevant for applications that automatically process ZIP files, such as web services, CI/CD pipelines, or automated file ingestion systems written in Go. Attackers could exploit this to disrupt services by causing resource exhaustion, potentially leading to downtime or degraded performance.

For European organizations, the primary impact of CVE-2025-61728 is the risk of denial of service through resource exhaustion when processing malicious ZIP archives. This can disrupt critical services, especially those that automatically handle ZIP files, such as cloud platforms, software build systems, and document management solutions. Organizations relying on Go-based applications in sectors like finance, healthcare, government, and telecommunications could face operational interruptions. The availability impact could cascade into financial losses, reputational damage, and compliance issues under regulations like GDPR if service disruptions affect customer data access. Since exploitation requires user interaction, phishing or social engineering could be vectors to deliver malicious ZIP files. The lack of known exploits currently reduces immediate risk but does not eliminate the threat, especially as attackers often weaponize such vulnerabilities post-disclosure. The absence of patches means organizations must rely on mitigations and monitoring until official fixes are released. Given the widespread use of Go in modern software stacks, the scope of affected systems is broad, increasing the potential impact across multiple industries in Europe.

1. Avoid processing ZIP archives from untrusted or unauthenticated sources, especially in automated workflows. 2. Implement strict resource limits (CPU time, memory usage) on processes handling ZIP files to prevent resource exhaustion. 3. Employ sandboxing or containerization for ZIP processing components to isolate potential DoS effects. 4. Monitor system and application logs for unusual CPU spikes or performance degradation during ZIP file handling. 5. Educate users and administrators about the risks of opening ZIP files from unknown origins to reduce user interaction exploitation. 6. Track Go project updates and apply patches promptly once available. 7. Consider alternative ZIP processing libraries or tools with known resistance to algorithmic complexity attacks if immediate patching is not feasible. 8. Integrate ZIP file scanning with security tools that can detect malformed or suspicious archive structures. 9. For critical systems, implement fallback mechanisms to maintain service availability if ZIP processing fails or is delayed. 10. Conduct regular security assessments and code reviews of applications using the Go archive/zip package to identify and mitigate potential abuse scenarios.