How much do you rely on Wi-Fi? The global standard for wireless internet connection appears to have just been hacked, according to security researchers who discovered a vulnerability that affects "almost all" devices.

So whether you're using Wi-Fi in a coffee shop on your tablet or at the office from a business laptop, chances are you're not safe any more.

That's the message coming from the United States Computer Emergency Readiness Team (US-CERT), which released the following statement: "US-CERT has become aware of several key management vulnerabilities in the 4-way handshake of the Wi-Fi Protected Access II (WPA2) security protocol.

"The impact of exploiting these vulnerabilities includes decryption, packet replay, TCP connection hijacking, HTTP content injection, and others."

The security exploit is known as Key Reinstallation Attacks (KRACK) and is a "protocol-level issue" meaning it's a problem with the Wi-Fi standard itself, not devices that are connected to it. According to experts speaking to Ars Technica , it means hackers can not only eavesdrop on communication sent over Wi-Fi but also actually inject malware and viruses into connected devices.

It's still not clear how this vulnerability might get fixed although some routers may be issued with a firmware update that closes it down. But given the sheer volume of WPA2-capable routers around the world, it's a daunting task to fight this latest cyber threat.

"WPA2 is currently the recommended option for securing your WI-FI network; the flaw, if successful, and if you’re not using any other advance features (VPN, encrypted data etc) could enable a hacker to eavesdrop on your data and or possibly gain access to any unsecured shares available on the same network," explained Mark James, a security specialist at ESET , an IT security company.