On November 30, 2021 MonoX was hacked for $31.4 million across Ethereum and Polygon when an attacker exploited a swap function that allowed same-asset swaps, using rapid swaps to manipulate the __updateTokenInfo function and artificially inflate MONO token price through a feedback loop, draining $18.2M WETH and $10.5M MATIC.

The automatic market maker protocol MonoX was hacked. In this attack, approximately US$18.2 million worth of WETH and 10.5 million US dollars of MATIC were stolen. Other stolen tokens included WBTC, LINK, GHST, DUCK, MIM and IMX. The total loss was approximately 31 million U.S. dollars.