Linus' reply on Git and SHA-1 collision
Pertinent facts for the worried:1) Git doesn't rely on SHA-1 for security. It relies on HTTPS, and a web of trust.2) Even if git did rely on SHA-1, there's no imminent threat.  What happened today was a SHA-1 collision, not a preimage attack.  If a collision costs 2^n, a preimage attack costs 2^(2n).3) Even if someone managed to pull off a preimage attack, creating a "poisonous" version of one your git repository's objects, they'd still have to convince you pull from their repo. This requires trust.4) Even if you pulled it in, your git client would simply ignore their "poison" object, because it would say, "oh, no thanks, I already have that object".  At worst, the code simply wouldn't work.  No harm would be done.When it comes to git, an attacker's time is better spent creating a secret buffer overflow than wasting millions of dollars on a SHA-1 collision.