Summary
Stirling-PDF contains an authorization bypass that may allow an authenticated user to access files belonging to another user by directing processing operations at that user's storage directory. If storage paths are accepted without verifying ownership, attackers could list, read, modify, or delete other users' files.
Stirling-PDF contains an authorization bypass that may allow an authenticated user to access files belonging to another user by directing processing operations at that user's storage directory. If storage paths are accepted without verifying ownership, attackers could list, read, modify, or delete other users' files.
Affected context
The issue may arise in Stirling-PDF deployments where authenticated users can create processing folders and supply a server-side storage path associated with another user. Risk is increased when folder creation, file listing, and pipeline execution do not enforce ownership checks for the targeted storage location.
The issue may arise in Stirling-PDF deployments where authenticated users can create processing folders and supply a server-side storage path associated with another user. Risk is increased when folder creation, file listing, and pipeline execution do not enforce ownership checks for the targeted storage location.
Exploit preconditions
- Attack surface: Authenticated processing-folder and pipeline API functionality
- Required access: A valid authenticated user account with permission to invoke the relevant endpoints
- Trigger point: Creating or selecting a processing folder that resolves to another user's storage directory
- Why exploitation is possible: Authorization is not sufficiently bound to the authenticated user's storage identity, allowing user-controlled path selection to cross ownership boundaries
- Attack surface: Authenticated processing-folder and pipeline API functionality
- Required access: A valid authenticated user account with permission to invoke the relevant endpoints
- Trigger point: Creating or selecting a processing folder that resolves to another user's storage directory
- Why exploitation is possible: Authorization is not sufficiently bound to the authenticated user's storage identity, allowing user-controlled path selection to cross ownership boundaries
Why this happens
The underlying flaw is an authorization decision that relies on a user-controlled storage reference without consistently verifying that the referenced directory belongs to the requesting user. This represents CWE-639: Authorization Bypass Through User-Controlled Key, where an identifier or path used to select a protected resource is accepted without an effective ownership or access-control check.
The underlying flaw is an authorization decision that relies on a user-controlled storage reference without consistently verifying that the referenced directory belongs to the requesting user. This represents CWE-639: Authorization Bypass Through User-Controlled Key, where an identifier or path used to select a protected resource is accepted without an effective ownership or access-control check.
Potential impact
- Authenticated users may access files belonging to other users
- Sensitive documents may be disclosed or exfiltrated
- Victims' files could be modified or replaced
- Stored files may be deleted or corrupted
- Document-processing workflows could be abused for cross-account data manipulation
- Authenticated users may access files belonging to other users
- Sensitive documents may be disclosed or exfiltrated
- Victims' files could be modified or replaced
- Stored files may be deleted or corrupted
- Document-processing workflows could be abused for cross-account data manipulation
General mitigation guidance
Mitigation generally focuses on enforcing server-side authorization for every storage operation.
Common defensive patterns include:
- Derive storage locations from the authenticated server-side identity rather than accepting arbitrary user-controlled paths
- Enforce ownership and tenant-boundary checks before folder creation, listing, reading, writing, or deletion
- Apply canonical path validation and restrict resolution to an approved per-user storage root
- Use deny-by-default access policies for storage and processing APIs
- Run processing services with only the filesystem permissions they require
- Avoid exposing predictable internal user identifiers as sufficient authorization references
Mitigation generally focuses on enforcing server-side authorization for every storage operation.
Common defensive patterns include:
- Derive storage locations from the authenticated server-side identity rather than accepting arbitrary user-controlled paths
- Enforce ownership and tenant-boundary checks before folder creation, listing, reading, writing, or deletion
- Apply canonical path validation and restrict resolution to an approved per-user storage root
- Use deny-by-default access policies for storage and processing APIs
- Run processing services with only the filesystem permissions they require
- Avoid exposing predictable internal user identifiers as sufficient authorization references
How teams detect issues like this
Organizations can look for:
- Static analysis patterns where request parameters or path components are used to construct filesystem locations
- Code review signals showing missing ownership checks around file and folder operations
- Tests that attempt cross-user access using valid accounts and alternate identifiers
- Runtime monitoring for requests targeting storage paths outside the authenticated user's assigned root
- Policy enforcement requiring explicit authorization checks before every read, write, list, rename, and delete operation
Automated application-security testing and access-control review tools may help identify these boundary violations.
Organizations can look for:
- Static analysis patterns where request parameters or path components are used to construct filesystem locations
- Code review signals showing missing ownership checks around file and folder operations
- Tests that attempt cross-user access using valid accounts and alternate identifiers
- Runtime monitoring for requests targeting storage paths outside the authenticated user's assigned root
- Policy enforcement requiring explicit authorization checks before every read, write, list, rename, and delete operation
Automated application-security testing and access-control review tools may help identify these boundary violations.
