The makers of Asterisk, the Open Source phone system, have removed a bug that allowed denial of service attacks under certain circumstances.
The vulnerability affected the SIP channel driver, more specifically the "BYE with Also" transfer method. A faulty null-pointer dereference could be exploited to crash the application using a carefully crafted BYE message. The attack needed an existing connection.
Updates are available from the website for the Open Source applications. Updates for commercial versions will be provided via standard support channels.
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