alt Hacker News> out-of-memory handling can interrupt PHP while internal request data is only partially initialized. Request cleanup may then treat the invalid data as valid.
If only we could come up with a way to manage memory automatically. Alas, one can only dream.
I'm pretty sure this class of problem would exist in GC'd environments too unless they're configured to abort on OOM, in which case you'd still be dealing with denial-of-service.
In some environments OOM is a trappable exception, so it's possible that incorrectly authored code would trap the OOM and 'recover' with partially initialized data sitting on the heap. Hopefully it's a memory-safe language so that partially initialized data isn't RCE...