nix/doc/manual/rl-next/fod-sandbox-escape.md

synopsis	issues	prs
Fix a FOD sandbox escape

Cooperating Nix derivations could send file descriptors to files in the Nix store to each other via Unix domain sockets in the abstract namespace. This allowed one derivation to modify the output of the other derivation, after Nix has registered the path as "valid" and immutable in the Nix database. In particular, this allowed the output of fixed-output derivations to be modified from their expected content.

This isn't the case any more.