CVE-2026-47898 in Lucene.Net
Summary
by MITRE • 07/03/2026
Improper Restriction of XML External Entity Reference vulnerability in Apache Lucene.Net (Lucene.Net.Analysis.Common library).
This issue affects Apache Lucene.Net.Analysis.Common: from 4.8.0-beta00005 before 4.8.0-beta00018.
Users are recommended to upgrade to version 4.8.0-beta00018, which fixes the issue.
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Analysis
by VulDB Data Team • 07/03/2026
The vulnerability under discussion represents a critical improper restriction of XML external entity reference flaw within Apache Lucene.Net's Analysis.Common library, specifically impacting versions ranging from 4.8.0-beta00005 through 4.8.0-beta00017. This weakness falls squarely within the scope of CWE-611, which categorizes insecure direct object references and XML external entity processing vulnerabilities. The flaw manifests when the library processes XML content without adequate validation or restriction of external entity references, creating potential attack vectors for malicious actors seeking to exploit the system.
The technical implementation of this vulnerability stems from insufficient sanitization of XML input within the Lucene.Net.Analysis.Common component, which is commonly used for text analysis and indexing operations in .NET applications. When processing documents containing XML data structures, the affected versions fail to properly restrict access to external entities, allowing attackers to craft malicious XML payloads that can trigger unwanted behavior during parsing operations. This vulnerability operates at the intersection of XML processing security and information disclosure risks, as it could potentially enable attackers to access local files or perform server-side request forgery attacks.
The operational impact of this vulnerability extends significantly across systems utilizing Apache Lucene.Net for document analysis and search functionality. Attackers could exploit this weakness by submitting crafted XML content that references external entities, potentially leading to unauthorized data access, denial of service conditions, or information leakage from the target system. The vulnerability's exploitation risk is particularly elevated in environments where untrusted user input is processed through the affected library components, as it creates opportunities for remote code execution or sensitive data exposure through XML external entity processing.
Mitigation strategies should prioritize immediate upgrade to version 4.8.0-beta00018, which implements proper restrictions on XML external entity references and includes comprehensive validation controls. Organizations should also implement additional defensive measures including input sanitization procedures, network segmentation to limit access to affected systems, and monitoring for suspicious XML processing activities. Security teams should consider implementing application firewalls or web application firewalls that can detect and block malicious XML content patterns, while also conducting thorough vulnerability assessments of all systems utilizing the affected library versions. The remediation approach aligns with ATT&CK technique T1213.002 for data from information repositories, as proper XML entity handling prevents unauthorized access to system resources through external reference exploitation.