Asterisk 1.4 before 1.4.1 and 1.2 before 1.2.16 allows remote attackers to cause a denial of service (crash) by sending a Session Initiation Protocol (SIP) packet without a URI and SIP-version header, which results in a NULL pointer dereference.
Unspecified vulnerability in the SIP channel driver (channels/chan_sip.c) in Asterisk 1.2.x before 1.2.13 and 1.4.x before 1.4.0-beta3 allows remote attackers to cause a denial of service (resource consumption) via unspecified vectors that result in the creation of "a real pvt structure" that uses more resources than necessary.
Stack-based buffer overflow in channels/chan_mgcp.c in MGCP in Asterisk 1.0 through 1.2.10 allows remote attackers to execute arbitrary code via a crafted audit endpoint (AUEP) response.
The IAX2 channel driver (chan_iax2) for Asterisk 1.2.x before 1.2.9 and 1.0.x before 1.0.11 allows remote attackers to cause a denial of service (crash) and execute arbitrary code via truncated IAX 2 (IAX2) video frames, which bypasses a length check and leads to a buffer overflow involving negative length check. NOTE: the vendor advisory claims that only a DoS is possible, but the original researcher is reliable.