[Zaak]

SHA-2 is based on similar techniques to those in SHA-1, which prompted the SHA-3 competition when weaknesses in SHA-1 were first discovered (as they could conceivably have been present in SHA-2 as well). As it turns out, SHA-2 appears to be resistant to the attacks found thus far.

SHA-3 (originally named Keccak) is built on an entirely different foundation (called a sponge function), so it is unlikely that any attack against SHA-1 will be relevant to SHA-3. However, sponge functions are a relatively new idea, and weaknesses in the basic principles could conceivably be found in the future, as could weaknesses in the Keccak algorithm specifically.