Mozilla urges Firefox users to patch browsers immediately

Firefox sign in front of a brick building
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Mozilla has released an emergency update to its Firefox browser to fix a critical vulnerability that is allowing attackers to seize control of users' machines.

Versions 67.0.3 and ESR 60.7.1 has been released to users on Windows, macOS and Linux desktop machines to mitigate a zero-day vulnerability dubbed CVE-2018-11707. The flaw does not arise or on Android, iOS or Amazon Fire TV iterations of the browser.

When exploited, it allows an attacker to execute arbitrary code on flawed machines and is being actively exploited in the wild, according to Mozilla. This could allow cyber criminals to seize full control if a system.

The critical vulnerability was discovered by Samuel Gro from Google Project Zero, and involves what is referred to as type confusion in Array.pop. When triggered, this can lead to an exploitable crash due to issues which occur when the browser attempts to manipulate JavaScript objects.

Mozilla deems a vulnerability to be 'critical' when it can be used to run code and install software without any user interaction required beyond normal browsing.

Highly severe zero-day flaws aren't uncommon, but they are often found and mitigated with patches by developers before cyber criminals are able to discover them and begin attacking users remotely.

The previous critical zero-day flaws that Mozilla discovered in Firefox 67 and Firefox ESR 60.7 were memory safety bugs flagged on 21 May this year. On this occasion, attackers were not found to be exploiting the vulnerabilities.

Another high-profile Firefox vulnerability was discovered last year by security researchers independent of Mozilla. After networking giant Cisco flagged an issue that could allow remote attackers to execute malicious code, the developers issued an emergency patch and urged users to update their browsers.

The news also comes at a time in which Mozilla is planning to introduce a host of security and privacy-centric features within Firefox, including tools such as secure storage, and a virtual private network (VPN).

Many of these new features could arise in a subscription-based version of the Firefox browser, which the developer last week hinted may surface before the end of 2019.

Keumars Afifi-Sabet

Keumars Afifi-Sabet is a writer and editor that specialises in public sector, cyber security, and cloud computing. He first joined ITPro as a staff writer in April 2018 and eventually became its Features Editor. Although a regular contributor to other tech sites in the past, these days you will find Keumars on LiveScience, where he runs its Technology section.