According to this, it only made it to test systems?

https://arstechnica.com/security/2024/03/backdoor-found-in-widely-used-linux-utility-breaks-encrypted-ssh-connections/

The University of Minnesota did something similar as a PoC a few years ago with the kernel.

https://www.theverge.com/2021/4/30/22410164/linux-kernel-university-of-minnesota-banned-open-source