Apple Security Advisory 2011-11-10-2 – Time Capsule and AirPort Base Station (802.11n) Firmware 7.6 is now available and addresses a security vulnerability. dhclient allowed remote attackers to execute arbitrary commands via shell metacharacters in a hostname obtained from a DHCP message. This issue is addressed by stripping shell meta-characters in dhclient-script.
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Apple Security Advisory 2011-11-10-2