Serious File Upload Vulnerability In Contact Form 7 Threatened Millions Of Websites

Heads up, WordPress admins. A critical vulnerability that potentially threatened the security of millions of websites has recently received a fix. Specifically, a file upload vulnerability in the WordPress plugin Contact Form 7 could allow an adversary to upload malicious content and inject codes on websites. While the fix is just out, make sure to have the latest plugin version 5.3.2 running on your websites.

Contact Form 7 Vulnerability

Researchers from the security firm Astra have recently discovered a critical file upload vulnerability in the Contact Form 7 plugin.

As elaborated in their blog post, the researchers observed an unrestricted file upload bug that could allow an attacker to upload malicious content on target websites.

By exploiting this vulnerability, attackers could simply upload files of any type, bypassing all restrictions placed regarding the allowed upload-able file types on a website. Further, it allows an attacker to inject malicious content such as web shells into the sites.

Specifically, an adversary could exploit the bug to inject malicious scripts, upload a web shell, or deface websites. Whereas, in situations where the servers lack containerization between websites, this vulnerability could allow the attacker to take over websites.

Patch Released – Update Now!

The vulnerability affected all plugin versions up to 5.3.1. It means also every other website running this plugin is prone to exploitation for now.

Thankfully, the Contact Form 7 plugin developer acted quickly to address the bugs.

While Astra researchers disclosed the bug to the developer yesterday, December 16, 2020, the developer managed to deploy a fix within a day.

Hence, on December 17, 2020, Contact Form 7 version 5.3.2 has been released with the fix.

Contact Form 7 is a popular WordPress plugin that facilitates websites in managing multiple contact forms simultaneously.

According to the plugin page, Contact Form 7 presently boasts over 5 million downloads. It means that the vulnerability also potentially affected millions of websites.

However, as usual, most websites are still running the older plugin versions. According to the stats available at the time of writing this article, only 30.6% of sites are running the plugin version 5.3. Whereas, a majority of sites (32.7%) are still running version 5.1.

Perhaps, that’s why the researchers have been kind enough to not disclose explicit details about the exploit. As they mentioned in their post, they will reveal further information after two weeks from today.

More details on the vulnerability will be added after a period of two weeks, to give users enough time to update and take necessary action to ensure they’re safe.

Now that the bug has caught attention, and the fix is out, all WordPress admins should ensure updating their websites with the latest plugin version at the earliest to avoid any mishap.