Hi,

Check Point researchers have discovered a vulnerability in the ITU T.30 fax protocol that could be hacked to launch a cyberattack and gain access to a network.

https://www.healthcareitnews.com/news/fax-machines-can-be-hacked-breach-network-using-only-its-number

The phrase above indicates a flaw in the T.30 protocol itself and not in particular implementations.

This is from 2018.

I don't remember reading anything about this in the fs mailing list.

Was freeswitch/spandsp audited to ensure application rxfax is safe?

https://blog.checkpoint.com/2018/08/12/faxploit-hp-printer-fax-exploit/