An exploiter took advantage of a flaw in USR's minting code to create tens of millions of USR tokens without depositing any assets to back them. The attacker then sold the unbacked USR, crashing the stablecoin's price to as low as $0.14. The attacker has profited at least 11,400 ETH (~$24 million), though they are still selling.
Some defi protocols paused USR-exposed strategies to avoid downstream impacts. Resolv issued a statement that the token's collateral pool was unaffected, though this is likely little comfort for those who purchased the unbacked USR.