Summary
Parse Server can bypass custom authentication checks when AuthAdapter subclasses define validation methods that are not invoked. An attacker may submit arbitrary authentication data to create accounts, link identities, log in as existing users, or bypass additional authentication factors when the affected adapter behavior is present.
Parse Server can bypass custom authentication checks when AuthAdapter subclasses define validation methods that are not invoked. An attacker may submit arbitrary authentication data to create accounts, link identities, log in as existing users, or bypass additional authentication factors when the affected adapter behavior is present.
Affected context
The issue occurs in Parse Server deployments using custom AuthAdapter subclasses with validation logic in methods such as validateSetUp, validateLogin, or validateUpdate. In affected releases and configurations, these methods may not be called, allowing an inherited default implementation to accept authentication data without the intended adapter-specific checks.
The issue occurs in Parse Server deployments using custom AuthAdapter subclasses with validation logic in methods such as validateSetUp, validateLogin, or validateUpdate. In affected releases and configurations, these methods may not be called, allowing an inherited default implementation to accept authentication data without the intended adapter-specific checks.
Exploit preconditions
- Attack surface: Parse Server authentication and identity-management endpoints
- Required access: The ability to send authentication-related requests to an exposed Parse Server application
- Trigger point: Account signup, login, identity linking, or authentication-factor processing through a custom AuthAdapter
- Why exploitation is possible: Custom validation callbacks are skipped, while an inherited permissive default accepts attacker-controlled authData
- Attack surface: Parse Server authentication and identity-management endpoints
- Required access: The ability to send authentication-related requests to an exposed Parse Server application
- Trigger point: Account signup, login, identity linking, or authentication-factor processing through a custom AuthAdapter
- Why exploitation is possible: Custom validation callbacks are skipped, while an inherited permissive default accepts attacker-controlled authData
Why this happens
The underlying bug is an authentication-control flow failure mapped to CWE-287: Improper Authentication. Parse Server fails to invoke adapter-specific validation methods and instead relies on an inherited implementation that treats supplied authentication data as valid. This causes security decisions to depend on unvalidated identity information rather than the custom authentication policy intended by the application.
The underlying bug is an authentication-control flow failure mapped to CWE-287: Improper Authentication. Parse Server fails to invoke adapter-specific validation methods and instead relies on an inherited implementation that treats supplied authentication data as valid. This causes security decisions to depend on unvalidated identity information rather than the custom authentication policy intended by the application.
Potential impact
- Attackers may create unauthorized accounts
- Attackers could log in as existing users
- User identities may be linked to attacker-controlled authentication data
- Additional authentication factors may be bypassed
- Applications can experience unauthorized data access or account takeover
- Attackers may create unauthorized accounts
- Attackers could log in as existing users
- User identities may be linked to attacker-controlled authentication data
- Additional authentication factors may be bypassed
- Applications can experience unauthorized data access or account takeover
General mitigation guidance
Mitigation generally focuses on ensuring that every authentication path invokes explicit, fail-closed validation logic.
Common defensive patterns include:
- Require custom adapters to implement and enforce authentication checks explicitly
- Reject missing, malformed, or unrecognized authentication data by default
- Ensure signup, login, update, and identity-linking flows share consistent validation policy
- Treat external identity claims and authentication attributes as untrusted until verified
- Apply least privilege to authenticated sessions and limit identity-linking capabilities
- Add independent checks for high-risk actions and additional authentication factors
- Use security tests that confirm invalid adapter data cannot authenticate or alter identities
Mitigation generally focuses on ensuring that every authentication path invokes explicit, fail-closed validation logic.
Common defensive patterns include:
- Require custom adapters to implement and enforce authentication checks explicitly
- Reject missing, malformed, or unrecognized authentication data by default
- Ensure signup, login, update, and identity-linking flows share consistent validation policy
- Treat external identity claims and authentication attributes as untrusted until verified
- Apply least privilege to authenticated sessions and limit identity-linking capabilities
- Add independent checks for high-risk actions and additional authentication factors
- Use security tests that confirm invalid adapter data cannot authenticate or alter identities
How teams detect issues like this
Organizations can look for this weakness through:
- Static analysis and code review checks for permissive default authentication methods
- Review of custom AuthAdapter subclasses to confirm every validation hook is invoked
- Tests covering invalid, forged, incomplete, and cross-user authentication data
- Monitoring for unexpected account creation, identity linking, and logins from unfamiliar sources
- Policy enforcement requiring authentication adapters to fail closed and document accepted authData fields
- Automated security review tools that flag authentication paths lacking explicit validation
Organizations can look for this weakness through:
- Static analysis and code review checks for permissive default authentication methods
- Review of custom AuthAdapter subclasses to confirm every validation hook is invoked
- Tests covering invalid, forged, incomplete, and cross-user authentication data
- Monitoring for unexpected account creation, identity linking, and logins from unfamiliar sources
- Policy enforcement requiring authentication adapters to fail closed and document accepted authData fields
- Automated security review tools that flag authentication paths lacking explicit validation
