TippingPoint Zero Day Initiative

(Pwn2Own) Apple macOS nsurlstoraged Null Pointer Dereference Denial of Service Vulnerability

ZDI-17-370: May 30th, 2017

CVSS Score

Affected Vendors

Affected Products


Vulnerability Details

This vulnerability allows local attackers to trigger a denial-of-service condition on vulnerable installations of Apple macOS. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.

The specific flaw exists within the nsurlstoraged service. The issue results from the lack of validating the existence of an object prior to performing operations on the object. An attacker can leverage this vulnerability to cause the service to restart.

Vendor Response

Apple states:

Regarding ZDI-CAN-4583, this was addressed by a mitigation. Multiple denial of service issues were addressed through improved memory handling. The finder has been acknowledged in our 'Additional recognition' section on the macOS Sierra 10.12.5 advisory at https://support.apple.com/HT207797.

Disclosure Timeline

    2017-03-17 - Vulnerability reported to vendor
    2017-05-30 - Coordinated public release of advisory


This vulnerability was discovered by:
    Niklas Baumstark and Samuel Gro