The Kamailio SIP before 5.5.0 server mishandles INVITE requests with duplicated fields and overlength tag, leading to a buffer overflow that crashes the server or possibly have unspecified other impact.

Kamailio before 5.4.0, as used in Sip Express Router (SER) in Sippy Softswitch 4.5 through 5.2 and other products, allows a bypass of a header-removal protection mechanism via whitespace characters. This occurs in the removehf function in the Kamailio textops module. Particular use of removehf in Sippy Softswitch may allow skilled attacker having a valid credential in the system to disrupt internal call start/duration accounting mechanisms leading potentially to a loss of revenue.

In Kamailio before 5.0.7 and 5.1.x before 5.1.4, a crafted SIP message with a double "To" header and an empty "To" tag causes a segmentation fault and crash. The reason is missing input validation in the "buildresbuffromsipreq" core function. This could result in denial of service and potentially the execution of arbitrary code.

Heap-based buffer overflow in the encodemsg function in encodemsg.c in the SEAS module in Kamailio (formerly OpenSER and SER) before 4.3.5 allows remote attackers to cause a denial of service (memory corruption and process crash) or possibly execute arbitrary code via a large SIP packet.

The kamcmd administrative utility and default configuration in kamailio before 4.3.0 use /tmp/kamailioctl.

In Kamailio before 5.0.7 and 5.1.x before 5.1.4, a crafted SIP message with an invalid Via header causes a segmentation fault and crashes Kamailio. The reason is missing input validation in the crcittstringarray core function for calculating a CRC hash for To tags. (An additional error is present in the checkviaaddress core function: this function also misses input validation.) This could result in denial of service and potentially the execution of arbitrary code.