CVE-2026-47896 in Lucene.Net
Summary
by MITRE • 07/03/2026
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in Apache Lucene.Net (Lucene.Net.Replicator library).
This issue affects Apache Lucene.Net.Replicator: from 4.8.0-beta00005 through 4.8.0-beta00017.
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 path traversal flaw within the Lucene.Net.Replicator library, specifically impacting versions ranging from 4.8.0-beta00005 through 4.8.0-beta00017. This weakness falls squarely under the category of improper limitation of pathname to restricted directories, a well-documented security concern that has been classified as CWE-22 within the Common Weakness Enumeration framework. The vulnerability stems from inadequate validation and sanitization of file paths during replication operations, creating an avenue for malicious actors to access unauthorized filesystem locations beyond the intended restricted directories.
The technical implementation flaw manifests when the replicator library processes file paths without sufficient input validation or canonicalization checks. During replication operations, the system accepts user-provided or external path references that are not properly sanitized before being used in filesystem operations. This allows attackers to craft malicious path sequences containing directory traversal characters such as "../" or "..\", enabling them to navigate outside of the intended directory boundaries and access sensitive files or directories that should remain restricted. The vulnerability becomes particularly dangerous in environments where the replicator service operates with elevated privileges, as it could potentially expose system-critical files, configuration data, or even allow for arbitrary file read/write operations.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable a wide range of malicious activities within affected systems. An attacker exploiting this path traversal vulnerability could potentially access application configuration files containing database credentials, encryption keys, or other sensitive information. The vulnerability also presents risks for remote code execution if the replicator service has write permissions to directories where executable files are stored, or if it can manipulate critical system files through the traversal mechanism. This weakness aligns with several techniques documented in the MITRE ATT&CK framework under the initial access and persistence phases, particularly leveraging path traversal for privilege escalation and lateral movement within compromised environments.
Organizations utilizing affected versions of Apache Lucene.Net.Replicator should immediately implement the recommended upgrade to version 4.8.0-beta00018, which incorporates proper input validation and path sanitization mechanisms. The fix addresses the core issue by implementing robust canonicalization checks that ensure all file paths are properly resolved within the intended directory boundaries before any filesystem operations are performed. Additional mitigations include implementing strict file access controls, monitoring for suspicious file access patterns, and ensuring the replicator service operates with minimal required privileges. Security teams should also conduct thorough vulnerability assessments to identify any potential exploitation attempts that may have occurred prior to the patch deployment, as this type of vulnerability often remains undetected until actively exploited in the wild.