Summary
Easy!Appointments contains an authorization bypass in the appointment registration flow that may allow unauthenticated users to alter appointments by supplying an appointment identifier without the expected authorization hash. An attacker could enumerate appointment IDs, change appointment and customer details, and obtain management hashes that enable later rescheduling or cancellation.
Easy!Appointments contains an authorization bypass in the appointment registration flow that may allow unauthenticated users to alter appointments by supplying an appointment identifier without the expected authorization hash. An attacker could enumerate appointment IDs, change appointment and customer details, and obtain management hashes that enable later rescheduling or cancellation.
Affected context
The issue occurs in deployments where the Booking::register() flow accepts an appointment ID without reliably requiring and validating its associated authorization hash. Risk is increased when appointment identifiers are predictable and request-controlled flags can influence management behavior before ownership or authorization is established.
The issue occurs in deployments where the Booking::register() flow accepts an appointment ID without reliably requiring and validating its associated authorization hash. Risk is increased when appointment identifiers are predictable and request-controlled flags can influence management behavior before ownership or authorization is established.
Exploit preconditions
- Attack surface: Public appointment booking or registration endpoints
- Required access: No authenticated account is generally required
- Trigger point: A request to the Booking::register() appointment-management flow
- Required knowledge: A valid or discoverable appointment identifier
- Why exploitation is possible: Authorization can be bypassed when the appointment ID is accepted without a valid hash, allowing attacker-controlled management parameters to influence updates
- Attack surface: Public appointment booking or registration endpoints
- Required access: No authenticated account is generally required
- Trigger point: A request to the Booking::register() appointment-management flow
- Required knowledge: A valid or discoverable appointment identifier
- Why exploitation is possible: Authorization can be bypassed when the appointment ID is accepted without a valid hash, allowing attacker-controlled management parameters to influence updates
Why this happens
The underlying bug is an authorization design failure in which possession of an appointment identifier is treated as sufficient authority to modify the corresponding record. This maps to CWE-639, Authorization Bypass Through User- Controlled Key, because a user-controlled identifier is used to select a protected object without consistently binding the operation to a separately verified authorization token, owner, or authenticated principal.
The underlying bug is an authorization design failure in which possession of an appointment identifier is treated as sufficient authority to modify the corresponding record. This maps to CWE-639, Authorization Bypass Through User- Controlled Key, because a user-controlled identifier is used to select a protected object without consistently binding the operation to a separately verified authorization token, owner, or authenticated principal.
Potential impact
- An attacker may modify appointment details without authorization
- Customer records may be rebound to attacker-controlled identities
- Management hashes could be exposed or generated for unauthorized users
- Appointments could be rescheduled or canceled
- Business operations and customer trust could be disrupted
- An attacker may modify appointment details without authorization
- Customer records may be rebound to attacker-controlled identities
- Management hashes could be exposed or generated for unauthorized users
- Appointments could be rescheduled or canceled
- Business operations and customer trust could be disrupted
General mitigation guidance
Mitigation generally focuses on enforcing authorization at the point of every
appointment read and write, rather than trusting identifiers or client-
supplied mode flags.
Common defensive patterns include:
- Requiring a valid, unguessable authorization token or authenticated owner context for each management operation
- Binding appointment-management credentials to the specific appointment and intended action
- Rejecting requests when authorization material is absent, malformed, expired, or mismatched
- Avoiding sequential identifiers as the sole access control mechanism
- Treating management-mode parameters as non-authoritative client input
- Applying least privilege to appointment-management services and administrative roles
- Logging and rate-limiting repeated identifier probing and unauthorized update attempts
Mitigation generally focuses on enforcing authorization at the point of every
appointment read and write, rather than trusting identifiers or client-
supplied mode flags.
Common defensive patterns include:
- Requiring a valid, unguessable authorization token or authenticated owner context for each management operation
- Binding appointment-management credentials to the specific appointment and intended action
- Rejecting requests when authorization material is absent, malformed, expired, or mismatched
- Avoiding sequential identifiers as the sole access control mechanism
- Treating management-mode parameters as non-authoritative client input
- Applying least privilege to appointment-management services and administrative roles
- Logging and rate-limiting repeated identifier probing and unauthorized update attempts
How teams detect issues like this
Detection approaches may include:
- Static analysis and code review for database updates selected directly by request-controlled IDs
- Checks that every appointment mutation performs an explicit ownership or authorization decision
- Review of code paths where mode flags, hashes, or identifiers are accepted from clients
- Dynamic tests that attempt access with missing, invalid, mismatched, and reused authorization tokens
- Monitoring for sequential appointment-ID enumeration, unusual update volume, and management-hash issuance
- Policy enforcement requiring authorization checks before protected-object mutations
Detection approaches may include:
- Static analysis and code review for database updates selected directly by request-controlled IDs
- Checks that every appointment mutation performs an explicit ownership or authorization decision
- Review of code paths where mode flags, hashes, or identifiers are accepted from clients
- Dynamic tests that attempt access with missing, invalid, mismatched, and reused authorization tokens
- Monitoring for sequential appointment-ID enumeration, unusual update volume, and management-hash issuance
- Policy enforcement requiring authorization checks before protected-object mutations
