According to the Daily Planet, the Ethereum programming language Vyper issued an announcement stating that "Vyper versions 0.2.15, 0.2.16, and 0.3.0 have a recursive lock vulnerability that causes functional failure. An investigation is currently underway, but any project using these versions should contact us immediately."
Curve officially responded: Due to a vulnerability in Vyper 0.2.15, some stablecoin pools (alETH/msETH/pETH) have been attacked. We are evaluating the situation and will release updates to the community as the situation develops. Other pools are safe.