The Asterisk project reports:
If an SDP offer or answer is received with the Opus
codec and with the format parameters separated using a
space the code responsible for parsing will recursively
call itself until it crashes. This occurs as the code
does not properly handle spaces separating the parameters.
This does NOT require the endpoint to have Opus configured
in Asterisk. This also does not require the endpoint to
be authenticated. If guest is enabled for chan_sip or
anonymous in chan_pjsip an SDP offer or answer is still
processed and the crash occurs.