Quantum Secular Labs / Blog / Advisories

CVE-2016-4658: Apple Tvos: Use after free

CVE-2016-4658 is rated critical with a CVSS v3.0 base score of 9.8 and affects Apple Tvos, along with 2 other products in NVD’s configuration data. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available.

Vulnerability description

xpointer.c in libxml2 before 2.9.5 (as used in Apple iOS before 10, OS X before 10.12, tvOS before 10, and watchOS before 3, and other products) does not forbid namespace nodes in XPointer ranges, which allows remote attackers to execute arbitrary code or cause a denial of service (use-after-free and memory corruption) via a crafted XML document.

Severity breakdown

CVSS v3.0 9.8: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
Attack complexity: Low. No special conditions; the attack can be repeated reliably.
Privileges required: None. No account or prior access is needed.
User interaction: None. No action from any user is needed.
Scope: Unchanged. Impact stays within the vulnerable component.
Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary.

Affected products

Apple Tvos: before 10.0
Apple Watchos: before 3.0
Xmlsoft Libxml2: before 2.9.5
Apple Iphone OS: before 10.0
Apple Mac OS X: before 10.12