CVE Vulnerabilities

CVE-2019-8662

Use After Free

Published: Dec 18, 2019 | Modified: Aug 24, 2020
CVSS 3.x
9.8
CRITICAL
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.x
7.5 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P
RedHat/V2
RedHat/V3
Ubuntu

This issue was addressed with improved checks. This issue is fixed in iOS 12.4, macOS Mojave 10.14.6, tvOS 12.4, watchOS 5.3. An attacker may be able to trigger a use-after-free in an application deserializing an untrusted NSDictionary.

Weakness

Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.

Affected Software

Name Vendor Start Version End Version
Iphone_os Apple * 12.4 (excluding)
Mac_os_x Apple * 10.14.6 (excluding)
Tvos Apple * 12.4 (excluding)
Watchos Apple * 5.3 (excluding)

Extended Description

The use of previously-freed memory can have any number of adverse consequences, ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw. The simplest way data corruption may occur involves the system’s reuse of the freed memory. Use-after-free errors have two common and sometimes overlapping causes:

In this scenario, the memory in question is allocated to another pointer validly at some point after it has been freed. The original pointer to the freed memory is used again and points to somewhere within the new allocation. As the data is changed, it corrupts the validly used memory; this induces undefined behavior in the process. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.

Potential Mitigations

References