CVE Vulnerabilities

CVE-2020-16929

Use After Free

Published: Oct 16, 2020 | Modified: Dec 31, 2023
CVSS 3.x
7.8
HIGH
Source:
NVD
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CVSS 2.x
6.8 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:P
RedHat/V2
RedHat/V3
Ubuntu

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
365_apps Microsoft - (including) - (including)
Excel Microsoft 2010-sp2 (including) 2010-sp2 (including)
Excel Microsoft 2013-sp1 (including) 2013-sp1 (including)
Excel Microsoft 2016 (including) 2016 (including)
Excel_web_app Microsoft 2010-sp2 (including) 2010-sp2 (including)
Office Microsoft 2010-sp2 (including) 2010-sp2 (including)
Office Microsoft 2013-sp1 (including) 2013-sp1 (including)
Office Microsoft 2016 (including) 2016 (including)
Office Microsoft 2019 (including) 2019 (including)
Office_online_server Microsoft 1.0 (including) 1.0 (including)
Office_web_apps Microsoft 2010-sp2 (including) 2010-sp2 (including)
Office_web_apps Microsoft 2013-sp1 (including) 2013-sp1 (including)
Sharepoint_enterprise_server Microsoft 2013-sp1 (including) 2013-sp1 (including)
Sharepoint_server Microsoft 2010-sp2 (including) 2010-sp2 (including)

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