Actively exploited vulnerability
Meta Platforms WhatsApp: cross-site scripting flaw under attack
CVE-2019-18426 · WhatsApp Cross-Site Scripting Vulnerability
What is affected
Meta Platforms WhatsApp 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.
A vulnerability in WhatsApp Desktop when paired with WhatsApp for iPhone allows cross-site scripting and local file reading.
What an attacker can do
This is a cross-site scripting flaw. It lets an attacker plant a script that runs in the browser of anyone who opens the affected page, which lets them steal that person's session or act on their behalf.
- 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
- Update Meta Platforms WhatsApp 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.
- Turn on automatic updates so the next fix arrives without you having to look for it.
- 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 May 23, 2022, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by June 13, 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 68% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 99.3% of all scored vulnerabilities.
Its CVSS severity score is 8.2 out of 10 (high), as recorded in the US National Vulnerability Database.
Technical description
A vulnerability in WhatsApp Desktop versions prior to 0.3.9309 when paired with WhatsApp for iPhone versions prior to 2.20.10 allows cross-site scripting and local file reading. Exploiting the vulnerability requires the victim to click a link preview from a specially crafted text message.