CVE-2019-9796 Explained : Impact and Mitigation

A use-after-free vulnerability affecting Thunderbird, Firefox ESR, and Firefox versions less than specified.

Understanding CVE-2019-9796

What is CVE-2019-9796?

This vulnerability occurs due to a double registration of the SMIL animation controller with the refresh driver, leading to a pointer retention issue.

The Impact of CVE-2019-9796

The vulnerability impacts Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66, potentially allowing attackers to execute arbitrary code.

Technical Details of CVE-2019-9796

Vulnerability Description

Use-after-free vulnerability caused by incorrect registration with the refresh driver
Pointer retention issue after removal of the animation controller element

Affected Systems and Versions

Thunderbird < 60.6
Firefox ESR < 60.6
Firefox < 66

Exploitation Mechanism

Attackers can exploit this vulnerability to execute arbitrary code by manipulating the dangling pointer left by the refresh driver.

Mitigation and Prevention

Immediate Steps to Take

Update Thunderbird, Firefox ESR, and Firefox to versions 60.6 and 66 or higher
Monitor vendor advisories for patches and security updates

Long-Term Security Practices

Regularly update software to the latest versions
Implement security best practices to prevent and detect similar vulnerabilities

Patching and Updates

Apply patches provided by Mozilla and other relevant vendors to address the vulnerability