Issue #19479 has been updated by jeremyevans0 (Jeremy Evans).
I submitted an upstream pull request to fix this:
https://github.com/ruby/ipaddr/pull/57
----------------------------------------
Bug #19479: Support IPv4-mapped IPv6 addresses in IPAddr#private?
https://bugs.ruby-lang.org/issues/19479#change-103664
* Author: tgxworld (Guo Xiang Tan)
* Status: Open
* Priority: Normal
* ruby -v: ruby 3.2.1 (2023-02-08 revision 31819e82c8) [x86_64-linux]
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
```
irb(main):010:0> IPAddr.new("172.16.0.0").private?
=> true
irb(main):011:0> IPAddr.new("::ffff:172.16.0.0").private?
=> false
```
If IPAddr#private? is used in a critical code path, not supporting IPv4-mapped IPv6
addresses could lead to security issues.
--
https://bugs.ruby-lang.org/