Summary
A path traversal vulnerability in Kavita allows unauthenticated attackers to access files outside the intended cover-upload temporary directory. The issue becomes risky when user-controlled filename values are used in filesystem operations without sufficient path canonicalization and boundary enforcement.
A path traversal vulnerability in Kavita allows unauthenticated attackers to access files outside the intended cover-upload temporary directory. The issue becomes risky when user-controlled filename values are used in filesystem operations without sufficient path canonicalization and boundary enforcement.
Affected context
The vulnerability occurs in Kavita's image cover-upload API when a request-controlled filename is incorporated into a local filesystem path. Deployments are at risk when the resulting path is not reliably confined to the designated temporary directory and the endpoint is reachable without authentication.
The vulnerability occurs in Kavita's image cover-upload API when a request-controlled filename is incorporated into a local filesystem path. Deployments are at risk when the resulting path is not reliably confined to the designated temporary directory and the endpoint is reachable without authentication.
Exploit preconditions
- Attack surface: HTTP GET requests to the cover-upload image API
- Required access: Network access to the exposed endpoint; authentication may not be required
- Trigger point: Processing of a user-controlled filename during file retrieval
- Why exploitation is possible: Relative path components can cause filesystem resolution outside the intended upload directory when canonicalization and directory-boundary checks are insufficient
- Attack surface: HTTP GET requests to the cover-upload image API
- Required access: Network access to the exposed endpoint; authentication may not be required
- Trigger point: Processing of a user-controlled filename during file retrieval
- Why exploitation is possible: Relative path components can cause filesystem resolution outside the intended upload directory when canonicalization and directory-boundary checks are insufficient
Why this happens
The underlying bug is improper limitation of a user-influenced filesystem path. The application uses a filename value to construct or resolve a local path without ensuring that the canonical result remains within the permitted directory. This behavior maps to CWE-22: Improper Limitation of a Pathname to a Restricted Directory, commonly known as path traversal.
The underlying bug is improper limitation of a user-influenced filesystem path. The application uses a filename value to construct or resolve a local path without ensuring that the canonical result remains within the permitted directory. This behavior maps to CWE-22: Improper Limitation of a Pathname to a Restricted Directory, commonly known as path traversal.
Potential impact
- Attackers may read sensitive application configuration files
- Exposed files could contain credentials, tokens, or internal service details
- Confidentiality of application and host data may be reduced
- Retrieved configuration information could support follow-on attacks
- Attackers may read sensitive application configuration files
- Exposed files could contain credentials, tokens, or internal service details
- Confidentiality of application and host data may be reduced
- Retrieved configuration information could support follow-on attacks
General mitigation guidance
Mitigation generally focuses on reducing trust in client-supplied path components and enforcing a strict filesystem boundary.
Common defensive patterns include:
- Accepting opaque file identifiers rather than raw filenames where practical
- Resolving paths canonically before access and verifying they remain under an approved directory
- Rejecting path separators, relative components, and unexpected filename formats
- Using allowlisted extensions and server-side generated names
- Applying least-privilege permissions to the application process and stored files
- Returning generic errors without revealing filesystem details
Mitigation generally focuses on reducing trust in client-supplied path components and enforcing a strict filesystem boundary.
Common defensive patterns include:
- Accepting opaque file identifiers rather than raw filenames where practical
- Resolving paths canonically before access and verifying they remain under an approved directory
- Rejecting path separators, relative components, and unexpected filename formats
- Using allowlisted extensions and server-side generated names
- Applying least-privilege permissions to the application process and stored files
- Returning generic errors without revealing filesystem details
How teams detect issues like this
Organizations can look for path traversal risks through:
- Static analysis rules identifying user input used in file-path construction
- Code review checks for canonicalization followed by directory-boundary validation
- Tests covering encoded, normalized, and platform-specific path variations
- Web-server and application logs showing unusual filename values or repeated file-read errors
- Policy enforcement that restricts filesystem access to approved application directories
Automated security review tools may help identify unsafe path handling patterns during development.
Organizations can look for path traversal risks through:
- Static analysis rules identifying user input used in file-path construction
- Code review checks for canonicalization followed by directory-boundary validation
- Tests covering encoded, normalized, and platform-specific path variations
- Web-server and application logs showing unusual filename values or repeated file-read errors
- Policy enforcement that restricts filesystem access to approved application directories
Automated security review tools may help identify unsafe path handling patterns during development.
