CVE-2025-47436 is a heap-based buffer overflow vulnerability identified in the Apache ORC C++ library, specifically within the LZO decompression logic. Apache ORC is a widely used columnar storage format optimized for big data processing. The vulnerability arises when the decompressor processes specially crafted malformed ORC files. In this scenario, the decompressor allocates a buffer of 250 bytes but attempts to copy 295 bytes into it, leading to memory corruption. This buffer overflow can potentially be exploited to execute arbitrary code, cause denial of service, or crash applications using the vulnerable library. The affected versions include Apache ORC C++ library versions through 1.8.8, from 1.9.0 through 1.9.5, from 2.0.0 through 2.0.4, and from 2.1.0 through 2.1.1. The issue has been addressed in versions 1.8.9, 1.9.6, 2.0.5, and 2.1.2. The CVSS 4.0 base score is 6.0 (medium severity), reflecting the complexity of exploitation (local access with privileges), partial user interaction, and moderate impact on confidentiality, integrity, and availability. The vulnerability requires local access with high privileges and partial user interaction, limiting remote exploitation but still posing a risk in environments where untrusted ORC files are processed. No known exploits are currently reported in the wild, but the vulnerability's nature warrants prompt attention due to potential memory corruption consequences.

For European organizations, the impact of this vulnerability depends largely on the use of Apache ORC in their data processing pipelines, especially in big data analytics, data warehousing, and cloud environments. Organizations handling large-scale data with Apache ORC C++ library could face risks of application crashes, data corruption, or potential privilege escalation if attackers can supply crafted ORC files. This is particularly critical for sectors relying on data integrity and availability such as finance, healthcare, telecommunications, and government agencies. The requirement for local high-privilege access and user interaction reduces the risk of widespread remote exploitation but does not eliminate insider threats or risks from compromised internal systems. Additionally, memory corruption vulnerabilities can be leveraged as part of multi-stage attacks to gain further system control. Disruption of data processing workflows could lead to operational downtime, regulatory compliance issues (e.g., GDPR), and reputational damage.

European organizations should prioritize upgrading Apache ORC C++ library to the fixed versions: 1.8.9, 1.9.6, 2.0.5, or 2.1.2 depending on their current deployment. Beyond patching, organizations should implement strict input validation and sanitization for ORC files, especially those sourced from untrusted or external origins. Employing application whitelisting and restricting the execution of code that processes ORC files to trusted users can reduce exploitation risk. Monitoring and logging decompression operations for anomalies may help detect exploitation attempts. Additionally, applying the principle of least privilege to limit high-privilege local access and enforcing multi-factor authentication can mitigate insider threats. Regularly auditing systems that utilize Apache ORC and integrating vulnerability scanning into the CI/CD pipeline will help identify outdated versions. Finally, organizations should prepare incident response plans for memory corruption incidents and ensure backups of critical data to minimize downtime.