macOS kernel return 53 (KERN_DENIED): meaning and diagnosis

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: Mach denied the operation through a security policy.

Could be also:
Constant	Type	OS
ERROR_BAD_NETPATH	Win32 error	Windows
EBADR	errno	Linux
ECONNABORTED	errno	Mac
ENOANO	errno	Solaris
NO_MORE_IRP_STACK_LOCATIONS	BugCheck Code	Windows

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KERN_INSUFFICIENT_BUFFER_SIZE	MACH_SEND_INVALID_DATA

KERN_DENIED

KERN_DENIED is the specific XNU kern_return_t for a request denied by security policy. It is more informative than a generic failure because the operation reached a policy gate; it still does not identify the exact policy, entitlement, authorization context, or rule that rejected the request.

Mach resources are commonly accessed through ports and port rights, but policy checks can also exist above the basic right model. Keep this result distinct from a VM protection failure and from an invalid port right: those conditions describe different layers and lead to different diagnostics.

Focused investigation

Identify the service, Mach interface, and target object that performed the policy check.
Collect relevant subsystem logs and the caller's signing or authorization context where applicable.
Confirm the intended operation is permitted by the public API instead of attempting to bypass the decision.
Preserve KERN_DENIED when mapping it to a higher-level error so policy failures remain distinguishable in telemetry.

References

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