Google Chromium V8: information disclosure flaw under attack

What is affected

Google Chromium V8 is found on ordinary personal computers and phones, so this is not only a problem for companies. If you use it and have not updated since the fix was released, you are exposed.

Google Chromium V8 Engine contains an out-of-bounds read vulnerability that allows a remote attacker to cause a denial of service or possibly have another unspecified impact via crafted JavaScript code. This vulnerability could affect multiple web browsers that utilize Chromium, including, but not limited to, Google Chrome, Microsoft Edge, and Opera.

What an attacker can do

This is a information disclosure flaw. It lets an attacker read data they are not supposed to see, such as memory contents, credentials or internal files. It is often the first step of a larger attack.

How it is reached

Over the internet or network

Access the attacker needs

No account needed

Does the victim have to do something?

Yes, the victim must open or click something

What to do

1. Update Google Chromium V8 now. Open the update or "About" screen, install whatever is offered and restart the app or device, because the fix is not active until you do.
2. Turn on automatic updates so the next fix arrives without you having to look for it.
3. If your device is too old to receive this update, stop using the affected app for anything sensitive and plan a replacement.

Apply updates per vendor instructions.

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on June 8, 2022, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by June 22, 2022, a deadline that has already passed. That deadline does not bind anyone else, but it shows how seriously the agency rates it.

The EPSS model estimates a 48% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 99% of all scored vulnerabilities.

Its CVSS severity score is 8.8 out of 10 (high), as recorded in the US National Vulnerability Database.

Technical description

The Array.prototype.concat implementation in builtins.cc in Google V8, as used in Google Chrome before 49.0.2623.108, does not properly consider element data types, which allows remote attackers to cause a denial of service (out-of-bounds read) or possibly have unspecified other impact via crafted JavaScript code.