So the most widely deployed and modern security protocol for 802.11 networks is WiFi Protected Access v2 (WPA2). If you use 802.11, then chances are you are using some form of this protocol for security.
But unfortunately, there has been a major breach of WPA2 at the protocol level. This isn't just a bug in one vendor's implementation of WPA2, but a direct attack on the protocol itself that appears to be effective against just about every widely deployed network stack.
While I haven't read the vulnerabilities in great detail, they appear to be directed to forcing re-use of a "nonce" (number-only-once). Nonces are very commonly used in many encryption protocols and as the name states, the numbers should only be used once to prevent replay attacks and leakage of information that occurs when encryption systems use the same basic key to encrypt multiple sets of data. Without nonces or other equivalent mechanisms, even a big cryptographically-secure protocols like AES can be cracked in a similar manner to how you crack the crypto-quip in a newspaper because they are using the same effective key (even if it is a big key) to encrypt multiple sets of data in a manner that can then easily be cracked. Additionally, in 802.11 if you can trick the system into re-using a nonce you could conceivably fool the authentication system into accepting your device by "replaying" an old handshake sequence from another legitimate device so that you can effectively bypass the need to know the password for the access point.
So basically: This is serious. Good news is that there are apparently some patches out to mitigate the issue but the bad news is that we all know that there are millions of wifi access points that don't get regular updates (or are flat out abandoned by their manufacturers) so even if a patch exists somewhere, your particular hardware is very likely still vulnerable.
