CVE-2023-37457 Asterisk's PJSIP_HEADER dialplan function can overwrite memory/cause crash when using 'update'

Asterisk is an open source private branch exchange and telephony toolkit. In Asterisk versions 18.20.0 and prior, 20.5.0 and prior, and 21.0.0; as well as ceritifed-asterisk 18.9-cert5 and prior, the 'update' functionality of the PJSIPHEADER dialplan function can exceed the available buffer space...