CVE Vulnerabilities

CVE-2020-0642

Use After Free

Published: Jan 14, 2020 | Modified: Apr 26, 2022
CVSS 3.x
7.8
HIGH
Source:
NVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 2.x
7.2 HIGH
AV:L/AC:L/Au:N/C:C/I:C/A:C
RedHat/V2
RedHat/V3
Ubuntu

An elevation of privilege vulnerability exists in Windows when the Win32k component fails to properly handle objects in memory, aka Win32k Elevation of Privilege Vulnerability. This CVE ID is unique from CVE-2020-0624.

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
Windows_server_2008 Microsoft r2 r2
Windows_server_2012 Microsoft r2 r2
Windows_server_2008 Microsoft r2 r2
Windows_10 Microsoft 1607 1607
Windows_8.1 Microsoft - -
Windows_server_2016 Microsoft - -
Windows_server_2008 Microsoft - -
Windows_7 Microsoft - -
Windows_rt_8.1 Microsoft - -
Windows_server_2012 Microsoft - -
Windows_10 Microsoft - -
Windows_10 Microsoft 1709 1709
Windows_10 Microsoft 1803 1803
Windows_server_2016 Microsoft 1803 1803
Windows_server_2019 Microsoft - -
Windows_10 Microsoft 1809 1809
Windows_server_2016 Microsoft 1903 1903
Windows_10 Microsoft 1903 1903
Windows_server_2016 Microsoft 1909 1909
Windows_10 Microsoft 1909 1909

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