Asterisk crashes when receiving a videocall over IAX2

Hello,

i have connected 2 FreePBX Systems via Dundi/IAX2 trunk. Normal calls are working fine, but when i activate Video on the phone A (Cisco, Yaelink...) and call another phone B (phone A >Server A >IAX2> Server B> phone B) Server B crashes. When i stay with phone A+B on the same Server or disable Video on the phone - everything works perfect. This only happens via IAX2 trunks, sometimes immediatly, sometimes after a while during the call.

The configuration of the trunk is very basic

dundi_custom.conf:

; DK0MAV
[22:e1:bc:08:83:5c]
host=44.149.94.136
include=priv
model=symmetric
order=primary
permit=priv
qualify=yes
secret=xxxxxxxxx

iax_custom.conf:

 [iaxuser]
type=friend
dbsecret=dundi/secret
context=incomingdundi

I already disabled videosupport on the IAX-Trunk but still the same issue.

Trace from the Asterisk-console of the crashing server:

Connected to Asterisk 16.2.1 currently running on freepbx (pid = 26623)
– Accepting AUTHENTICATED call from 44.225.66.196:4569:
– > requested format = g722,
– > requested prefs = disabled,
– > actual format = g722,
– > host prefs = disabled,
– > priority = disabled
– Executing [315200612183@incomingdundi:1] Playback("IAX2/iaxuser-5566", "custom/voip-dk0mav") in new stack
– <IAX2/iaxuser-5566> Playing 'custom/voip-dk0mav.g722' (language 'en')
[2021-04-12 21:49:48] WARNING[26669]: chan_iax2.c:11782 socket_process_helper: Received mini frame before first full video frame
freepbx*CLI> <<<<<<<<<<<<<<<<crash>>>>>>>>>>>>>>>
Disconnected from Asterisk server
Asterisk cleanly ending (0).
Executing last minute cleanups

I have tried to downgrade to an older Asterisk version but no success.

Just for clarification:

I do not want video working via IAX-Trunks, that seems not possible for what reason ever. I just want that Asterisk do not crash when it receives a call from a phone that has video enabled via the trunk.

The same configuration on earlier Asterisk versions (11, 13) is working without any problems.

It seems Asterisk have a problem when frames are lost on the trunk and they arrive in a kind of wrong order. This leads to a crash.

Maybe interesting but very old issue: https://www.coresecurity.com/core-labs/advisories/asterisk-pbx-truncated-video-frame-vulnerability

Please help me.

Best Regards

Michael