Summary
KodExplorer contains a path traversal weakness in ZIP extraction that can allow an authenticated attacker to overwrite files outside the intended extraction directory. Overwriting web-accessible assets may enable stored cross-site scripting, administrator account takeover, and potentially remote code execution when unrestricted PHP uploads are available.
KodExplorer contains a path traversal weakness in ZIP extraction that can allow an authenticated attacker to overwrite files outside the intended extraction directory. Overwriting web-accessible assets may enable stored cross-site scripting, administrator account takeover, and potentially remote code execution when unrestricted PHP uploads are available.
Affected context
The vulnerability occurs in KodExplorer deployments that accept authenticated ZIP uploads and extract archive contents using the affected filename sanitization and archive-extraction behavior. Risk is higher when uploaded archives can influence files outside the intended destination, when core web assets are writable, or when PHP files can be uploaded and executed by the application server.
The vulnerability occurs in KodExplorer deployments that accept authenticated ZIP uploads and extract archive contents using the affected filename sanitization and archive-extraction behavior. Risk is higher when uploaded archives can influence files outside the intended destination, when core web assets are writable, or when PHP files can be uploaded and executed by the application server.
Exploit preconditions
- Attack surface: Authenticated ZIP archive upload and extraction functionality
- Required access: Credentials or an application role permitted to upload archives
- Trigger point: Archive extraction through the KodExplorer file-management workflow
- Why exploitation is possible: A single non-recursive filename sanitization pass can be bypassed by crafted traversal sequences, while extraction does not enforce a destination-directory restriction
- Additional conditions for chaining: The targeted files must be writable, reachable by users or administrators, or executable by the server for later-stage impact
- Attack surface: Authenticated ZIP archive upload and extraction functionality
- Required access: Credentials or an application role permitted to upload archives
- Trigger point: Archive extraction through the KodExplorer file-management workflow
- Why exploitation is possible: A single non-recursive filename sanitization pass can be bypassed by crafted traversal sequences, while extraction does not enforce a destination-directory restriction
- Additional conditions for chaining: The targeted files must be writable, reachable by users or administrators, or executable by the server for later-stage impact
Why this happens
The underlying bug is improper neutralization of path traversal sequences in archive member filenames, mapping to CWE-22: Improper Limitation of a Pathname to a Restricted Directory. The application performs an insufficient string replacement rather than canonicalizing paths and verifying that every extracted destination remains within the intended directory. The archive extraction operation also lacks an independent containment restriction, allowing sanitized-looking but semantically unsafe paths to escape the target directory.
The underlying bug is improper neutralization of path traversal sequences in archive member filenames, mapping to CWE-22: Improper Limitation of a Pathname to a Restricted Directory. The application performs an insufficient string replacement rather than canonicalizing paths and verifying that every extracted destination remains within the intended directory. The archive extraction operation also lacks an independent containment restriction, allowing sanitized-looking but semantically unsafe paths to escape the target directory.
Potential impact
- An attacker may overwrite arbitrary files accessible to the extraction process
- Stored cross-site scripting could be introduced into web-accessible JavaScript or other assets
- Administrator sessions or accounts could be compromised through the modified content
- Application integrity and availability could be affected
- Remote code execution could occur if the attacker can ultimately place and execute a PHP file
- Additional application or server data could be exposed or modified
- An attacker may overwrite arbitrary files accessible to the extraction process
- Stored cross-site scripting could be introduced into web-accessible JavaScript or other assets
- Administrator sessions or accounts could be compromised through the modified content
- Application integrity and availability could be affected
- Remote code execution could occur if the attacker can ultimately place and execute a PHP file
- Additional application or server data could be exposed or modified
General mitigation guidance
Mitigation generally focuses on enforcing extraction containment independently of filename filtering and reducing trust in uploaded archives.
Common defensive patterns include:
- Canonicalizing each archive member path before extraction
- Rejecting absolute paths, parent-directory components, and platform-specific traversal forms
- Enforcing a destination-directory restriction for the archive library
- Verifying that the resolved output path remains beneath the intended extraction root
- Extracting uploads into isolated, non-web-accessible temporary storage
- Allowing only necessary archive formats and validating archive contents against a strict policy
- Preventing execution of uploaded scripts and restricting PHP handling in upload directories
- Running the application with the minimum filesystem permissions required
- Applying integrity protection or read-only controls to core application assets where practical
Mitigation generally focuses on enforcing extraction containment independently of filename filtering and reducing trust in uploaded archives.
Common defensive patterns include:
- Canonicalizing each archive member path before extraction
- Rejecting absolute paths, parent-directory components, and platform-specific traversal forms
- Enforcing a destination-directory restriction for the archive library
- Verifying that the resolved output path remains beneath the intended extraction root
- Extracting uploads into isolated, non-web-accessible temporary storage
- Allowing only necessary archive formats and validating archive contents against a strict policy
- Preventing execution of uploaded scripts and restricting PHP handling in upload directories
- Running the application with the minimum filesystem permissions required
- Applying integrity protection or read-only controls to core application assets where practical
How teams detect issues like this
Organizations can identify similar issues through:
- Static analysis rules for archive extraction without destination restrictions
- Code review checks for string-only traversal filtering, non-canonical path comparisons, and direct use of archive member names
- Tests covering encoded, repeated, mixed-separator, absolute, and parent-directory path forms
- Monitoring archive extraction events and writes outside approved upload directories
- File-integrity monitoring for unexpected changes to application assets and server-side scripts
- Policy enforcement that blocks executable content in user-controlled upload locations
- Automated security review tools that flag archive path handling and unrestricted upload combinations
Organizations can identify similar issues through:
- Static analysis rules for archive extraction without destination restrictions
- Code review checks for string-only traversal filtering, non-canonical path comparisons, and direct use of archive member names
- Tests covering encoded, repeated, mixed-separator, absolute, and parent-directory path forms
- Monitoring archive extraction events and writes outside approved upload directories
- File-integrity monitoring for unexpected changes to application assets and server-side scripts
- Policy enforcement that blocks executable content in user-controlled upload locations
- Automated security review tools that flag archive path handling and unrestricted upload combinations
