On a whim I opened up the:
Legal Disclaimer Open Source Licenses
in the management page for my fiber modem (ATT installed 2021/03/30) and discovered that the kernel is rather old:
linux kernel - Version 3.4.11
There are about 163 other open source components, probably most of similar ages.

Is this a security problem?

-- 
Sincerely Jonathan Ryshpan <jonrysh@pacbell.net>

	The above message, which does not represent 
	the opinion of the Berkeley Linux Team, is sold 
	by weight, not by volume.  
	Some settling of the contents may have occurred
	during shipment.