CVE-2025-27553
📋 TL;DR
This CVE describes a path traversal vulnerability in Apache Commons VFS where encoded '..' sequences (%2E%2E) bypass the NameScope.DESCENDENT validation in the resolveFile method. This allows attackers to access files outside the intended directory structure. Applications using Commons VFS for file operations are affected.
💻 Affected Systems
- Apache Commons VFS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could read, modify, or delete sensitive system files, potentially leading to data theft, system compromise, or denial of service.
Likely Case
Unauthorized file access within the application's file system context, potentially exposing configuration files, logs, or other sensitive data.
If Mitigated
Limited impact if proper file system permissions restrict access to sensitive directories and files.
🎯 Exploit Status
Exploitation requires the attacker to control input to the resolveFile method with encoded path traversal sequences.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.10.0
Vendor Advisory: https://lists.apache.org/thread/cnzqowyw9r2pl263cylmxhnvh41hyjcb
Restart Required: No
Instructions:
1. Update Commons VFS dependency to version 2.10.0 or later. 2. Rebuild and redeploy affected applications. 3. Test file operations to ensure functionality.
🔧 Temporary Workarounds
Input validation and sanitization
allImplement custom validation to reject paths containing encoded '..' sequences before passing to resolveFile.
🧯 If You Can't Patch
- Implement strict file system permissions to limit accessible directories.
- Use application-level access controls to restrict file operations.
🔍 How to Verify
Check if Vulnerable:
Check if your application uses Apache Commons VFS version below 2.10.0 and calls resolveFile with NameScope.DESCENDENT.Check Version:
Check your build configuration (Maven pom.xml, Gradle build.gradle) or run: java -cp commons-vfs2.jar org.apache.commons.vfs2.VersionVerify Fix Applied:
Verify Commons VFS version is 2.10.0 or higher in your dependency management system.📡 Detection & Monitoring
Log Indicators:
- Unusual file access patterns, failed file operations with encoded paths
SIEM Query:
Look for file access events involving encoded characters like %2E%2E in paths.