Asterisk Project Security Advisory - A crash can occur in Asterisk when a SIP message is received that has a History-Info header, which contains a tel-uri. Note, the remote client must be authenticated, or Asterisk must be configured for anonymous calling in order for this problem to manifest.
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Asterisk Project Security Advisory - If no UDPTL packets are lost there is no problem. However, a lost packet causes Asterisk to use the available error correcting redundancy packets. If those redundancy packets have zero length then Asterisk uses an uninitialized buffer pointer and length value which can cause invalid memory accesses later when the packet is copied.
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