CVE Vulnerabilities


Use After Free

Published: Jul 23, 2019 | Modified: Jul 25, 2019
CVSS 3.x
CVSS 2.x
7.5 HIGH

A use-after-free vulnerability can occur when listeners are removed from the event listener manager while still in use, resulting in a potentially exploitable crash. This vulnerability affects Thunderbird < 60.7, Firefox < 67, and Firefox ESR < 60.7.


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
Firefox Mozilla * 67.0 (excluding)
Firefox_esr Mozilla * 60.7.0 (excluding)
Thunderbird Mozilla * 60.7.0 (excluding)
Red Hat Enterprise Linux 6 RedHat firefox-0:60.7.0-1.el6_10 *
Red Hat Enterprise Linux 6 RedHat thunderbird-0:60.7.0-1.el6_10 *
Red Hat Enterprise Linux 7 RedHat firefox-0:60.7.0-1.el7_6 *
Red Hat Enterprise Linux 7 RedHat thunderbird-0:60.7.0-1.el7_6 *
Red Hat Enterprise Linux 8 RedHat firefox-0:60.7.0-1.el8_0 *
Red Hat Enterprise Linux 8 RedHat thunderbird-0:60.7.0-1.el8_0 *
Firefox Ubuntu bionic *
Firefox Ubuntu cosmic *
Firefox Ubuntu devel *
Firefox Ubuntu disco *
Firefox Ubuntu eoan *
Firefox Ubuntu focal *
Firefox Ubuntu groovy *
Firefox Ubuntu hirsute *
Firefox Ubuntu impish *
Firefox Ubuntu jammy *
Firefox Ubuntu kinetic *
Firefox Ubuntu lunar *
Firefox Ubuntu mantic *
Firefox Ubuntu noble *
Firefox Ubuntu upstream *
Firefox Ubuntu xenial *
Mozjs38 Ubuntu bionic *
Mozjs52 Ubuntu bionic *
Mozjs52 Ubuntu cosmic *
Mozjs52 Ubuntu disco *
Mozjs52 Ubuntu eoan *
Mozjs52 Ubuntu groovy *
Mozjs60 Ubuntu cosmic *
Mozjs60 Ubuntu disco *
Mozjs60 Ubuntu eoan *
Thunderbird Ubuntu bionic *
Thunderbird Ubuntu cosmic *
Thunderbird Ubuntu devel *
Thunderbird Ubuntu disco *
Thunderbird Ubuntu eoan *
Thunderbird Ubuntu focal *
Thunderbird Ubuntu groovy *
Thunderbird Ubuntu hirsute *
Thunderbird Ubuntu impish *
Thunderbird Ubuntu jammy *
Thunderbird Ubuntu kinetic *
Thunderbird Ubuntu lunar *
Thunderbird Ubuntu mantic *
Thunderbird Ubuntu noble *
Thunderbird Ubuntu upstream *
Thunderbird Ubuntu xenial *

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