The IAX2 protocol implementation in Asterisk Open Source 1.0.x, 1.2.x before 1.2.30, and 1.4.x before 1.4.21.2; Business Edition A.x.x, B.x.x before B.2.5.4, and C.x.x before C.1.10.3; AsteriskNOW; Appliance Developer Kit 0.x.x; and s800i 1.0.x before 1.2.0.1 allows remote attackers to cause a denial of service (call-number exhaustion and CPU consumption) by quickly sending a large number of IAX2 (IAX) POKE requests.

Asterisk Open Source 1.0.x and 1.2.x before 1.2.29 and Business Edition A.x.x and B.x.x before B.2.5.3, when pedantic parsing (aka pedanticsipchecking) is enabled, allows remote attackers to cause a denial of service (daemon crash) via a SIP INVITE message that lacks a From header, related to invocations of the ast_uri_decode function, and improper handling of (1) an empty const string and (2) a NULL pointer.

The IAX2 channel driver (chan_iax2) in Asterisk 1.2 before revision 72630 and 1.4 before revision 65679, when configured to allow unauthenticated calls, sends "early audio" to an unverified source IP address of a NEW message, which allows remote attackers to cause a denial of service (traffic amplification) via a spoofed NEW message.

The IAX2 channel driver (chan_iax2) in Asterisk Open Source 1.0.x, 1.2.x before 1.2.28, and 1.4.x before 1.4.19.1; Business Edition A.x.x, B.x.x before B.2.5.2, and C.x.x before C.1.8.1; AsteriskNOW before 1.0.3; Appliance Developer Kit 0.x.x; and s800i before 1.1.0.3, when configured to allow unauthenticated calls, does not verify that an ACK response contains a call number matching the server's reply to a NEW message, which allows remote attackers to cause a denial of service (traffic amplification) via a spoofed ACK response that does not complete a 3-way handshake. NOTE: this issue exists because of an incomplete fix for CVE-2008-1923.

The AsteriskGUI HTTP server in Asterisk Open Source 1.4.x before 1.4.19-rc3 and 1.6.x before 1.6.0-beta6, Business Edition C.x.x before C.1.6, AsteriskNOW before 1.0.2, Appliance Developer Kit before revision 104704, and s800i 1.0.x before 1.1.0.2 generates insufficiently random manager ID values, which makes it easier for remote attackers to hijack a manager session via a series of ID guesses.

Multiple buffer overflows in Asterisk Open Source 1.4.x before 1.4.18.1 and 1.4.19-rc3, Open Source 1.6.x before 1.6.0-beta6, Business Edition C.x.x before C.1.6.1, AsteriskNOW 1.0.x before 1.0.2, Appliance Developer Kit before 1.4 revision 109386, and s800i 1.1.x before 1.1.0.2 allow remote attackers to (1) write a zero to an arbitrary memory location via a large RTP payload number, related to the ast_rtp_unset_m_type function in main/rtp.c; or (2) write certain integers to an arbitrary memory location via a large number of RTP payloads, related to the process_sdp function in channels/chan_sip.c.

Unspecified vulnerability in Asterisk Open Source 1.2.x before 1.2.27, 1.4.x before 1.4.18.1 and 1.4.19-rc3; Business Edition A.x.x, B.x.x before B.2.5.1, and C.x.x before C.1.6.2; AsteriskNOW 1.0.x before 1.0.2; Appliance Developer Kit before 1.4 revision 109393; and s800i 1.0.x before 1.1.0.2; allows remote attackers to access the SIP channel driver via a crafted From header.

The SIP channel driver in Asterisk Open Source 1.4.x before 1.4.17, Business Edition before C.1.0-beta8, AsteriskNOW before beta7, Appliance Developer Kit before Asterisk 1.4 revision 95946, and Appliance s800i 1.0.x before 1.0.3.4 allows remote attackers to cause a denial of service (daemon crash) via a BYE message with an Also (Also transfer) header, which triggers a NULL pointer dereference.

Asterisk Open Source 1.2.x before 1.2.26 and 1.4.x before 1.4.16, and Business Edition B.x.x before B.2.3.6 and C.x.x before C.1.0-beta8, when using database-based registrations ("realtime") and host-based authentication, does not check the IP address when the username is correct and there is no password, which allows remote attackers to bypass authentication using a valid username.

Stack-based buffer overflow in the IAX2 channel driver (chan_iax2) in Asterisk before 1.2.22 and 1.4.x before 1.4.8, Business Edition before B.2.2.1, AsteriskNOW before beta7, Appliance Developer Kit before 0.5.0, and s800i before 1.0.2 allows remote attackers to execute arbitrary code by sending a long (1) voice or (2) video RTP frame.