CVE Vulnerabilities

CVE-2018-16294

Use After Free

Published: Oct 08, 2018 | Modified: Nov 21, 2018
CVSS 3.x
7.8
HIGH
Source:
NVD
CVSS:3.0/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

An exploitable use-after-free vulnerability exists in the JavaScript engine of Foxit Reader before 9.3 and PhantomPDF before 9.3, a different vulnerability than CVE-2018-16291, CVE-2018-16292, CVE-2018-16293, CVE-2018-16295, CVE-2018-16296, and CVE-2018-16297. A specially crafted PDF document can trigger a previously freed object in memory to be reused, resulting in arbitrary code execution. An attacker needs to trick the user to open the malicious file to trigger this vulnerability. If the browser plugin extension is enabled, visiting a malicious site can also trigger the vulnerability.

Weakness

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

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 chances 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