Canonical has published details about WPA and WPA2 vulnerability in Ubuntu and has released updates to fix these issues.
Kostya Kortchinsky discovered multiple flaws in wpa_supplicant and hostapd. According to the security notice from Canonical “A remote attacker could use these issues to cause wpa_supplicant or hostapd to crash, resulting in a denial of service. (CVE-2015-4141, CVE-2015-4142, CVE-2015-4143, CVE-2015-4144, CVE-2015-4145, CVE-2015-4146).”
If you run the Ubuntu Update Manager application the affected packages (hostapd and wpasupplicant) will be patched. Or you can run the following apt-get commands to apply the patch;
sudo apt-get update
sudo apt-get dist-upgrade
Read more about the vulnerability here.