Google Chromium Mojo: vulnerability flaw under attack

What is affected

Google Chromium Mojo 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 Mojo on Windows contains a sandbox escape vulnerability caused by a logic error, which results from an incorrect handle being provided in unspecified circumstances. 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 vulnerability flaw. It lets an attacker misuse the product in a way its maker did not intend. CISA lists it because attackers are confirmed to be using it against real systems.

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 Mojo 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 mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Vendor advisories and fixes

• chromereleases.googleblog.comchromereleases.googleblog.com/2025/03/stable-channel-update-for-desktop_25.html

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on March 27, 2025, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by April 17, 2025, 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 9.2% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 95% of all scored vulnerabilities.

Its CVSS severity score is 8.3 out of 10 (high), as recorded in the US National Vulnerability Database.

Technical description

Incorrect handle provided in unspecified circumstances in Mojo in Google Chrome on Windows prior to 134.0.6998.177 allowed a remote attacker to perform a sandbox escape via a malicious file. (Chromium security severity: High)