Mozilla fixes two Firefox zero-days being actively exploited

Critical vulnerabilities allow attackers to execute arbitrary code or trigger crashes

Firefox icon

Mozilla has moved fast to fix two Firefox browser zero-day vulnerabilities being actively exploited in the wild.

The flaws are both "use-after-free" vulnerabilities that could potentially allow attackers to execute arbitrary code or trigger crashes on machines running vulnerable versions of the Firefox browser.

The first bug, tracked as CVE-2020-6819, is tied to the browser component “nsDocShell destructor”, while the second zero-day, CVE-2020-6820, is linked to a race condition in the ReadableStream class, which is used to read a stream of data.

Advertisement - Article continues below

As per Mozilla's security advisory, the Firefox developers "are aware of targeted attacks in the wild abusing" these two critical flaws. However, details about the actual attacks where these two bugs are being exploited are still kept under wraps.

“Successful exploitation of the most severe of these vulnerabilities could allow for arbitrary code execution,” according to a Center for Internet Security bulletin

“Depending on the privileges associated with the user, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than those who operate with administrative user rights.”

The discovery of these vulnerabilities was credited to security researchers Francisco Alonso and Javier Marcos. Alonso tweeted there are “more details to be published (including other browsers),” indicating these flaws likely also affect other web browsers. 

Advertisement
Advertisement - Article continues below
Advertisement - Article continues below

Fixes are available in Firefox 74.0.1 and are also available for Firefox 68 users with version 68.6.

Mozilla patched another actively exploited Firefox zero-day with the release of Firefox 72.0.1 in January, which it also warned was being used in targeted attacks. This critical flaw, branded CVE-2019-17026, allowed an attacker to seize control of an affected computer through a mechanism that leads to ‘type confusion’.

Featured Resources

Key considerations for implementing secure telework at scale

Identifying the security risks and advanced requirements of a remote workforce

Download now

The State of Salesforce 2020

Your guide to getting the most from Salesforce

Download now

Fast, flexible and compliant e-signatures for global businesses

Be at the forefront of digital transformation with electronic signatures

Download now

Rethink your cybersecurity strategy for the new world

5 steps to secure the enterprise and be fit for a flexible future

Download now
Advertisement

Recommended

Andrew Daniels joins Druva as CIO and CISO
Cloud

Andrew Daniels joins Druva as CIO and CISO

22 Jul 2020
Why I’m leading a browser double life
web browser

Why I’m leading a browser double life

8 Jul 2020
University of California gets fleeced by hackers for $1.14 million
ransomware

University of California gets fleeced by hackers for $1.14 million

30 Jun 2020
Australia announces $1.35 billion investment in cyber security
cyber security

Australia announces $1.35 billion investment in cyber security

30 Jun 2020

Most Popular

How to find RAM speed, size and type
Laptops

How to find RAM speed, size and type

3 Aug 2020
How to use Chromecast without Wi-Fi
Mobile

How to use Chromecast without Wi-Fi

4 Aug 2020
Police use of facial recognition ruled unlawful in the UK
privacy

Police use of facial recognition ruled unlawful in the UK

11 Aug 2020