You are missing the forest for the trees. Grandparent is saying "replace all C with Rust" and you replied with "but look, Rust programs rely on glibc! It's unsafe!"
Yes, Rust programs can be affected by this. But only because they call into C at a lower level, for the libc layer. If glibc was in Rust it would provide security to all application, including ssh or curl which aren't in Rust.
Also, extern "C" is for C FFI exports not calling C APIs. The world unanimously decided C FFI is the least common denominator, so its not like Rust can provide a different API with better safety hints.
Yes, Rust programs can be affected by this. But only because they call into C at a lower level, for the libc layer. If glibc was in Rust it would provide security to all application, including ssh or curl which aren't in Rust.
Also, extern "C" is for C FFI exports not calling C APIs. The world unanimously decided C FFI is the least common denominator, so its not like Rust can provide a different API with better safety hints.