Go Ethereum (aka geth) through 1.10.21 allows attackers to increase rewards by mining blocks in certain situations, and using a manipulation of time-difference values to achieve replacement of main-chain blocks, aka Riskless Uncle Making (RUM), as exploited in the wild in 2020 through 2022.
https://github.com/advisories/GHSA-rqmg-hrg4-fm69
https://news.ycombinator.com/item?id=32354896