@bot @p@bae.st @sjw @matty @tyler @graf @Moon @p@shitposter.club oh. I don't know your level of technical sophistication, so I'm going to ELY5, no offense intended.
SSH is a program that runs on servers so that operators can securely remotely connect to them for management purposes.
The ssh program that runs on the server relies on the library provided by the xz project, liblzma.
The authors of the xz project inserted a backdoor to allow unauthorized access to SSH if the backdoored version of xz was installed.