The Ethereum Foundation has raised the maximum reward for its bug bounty program from $250,000 to $1 million, according to a tweet by security researcher Fredrik. The expanded bounty applies to vulnerabilities in specifications, client software, language compilers, deposit contracts, and dependency errors. However, it excludes infrastructure vulnerabilities such as those in websites, DNS, and email, as well as ERC-20 contract and Ethereum Name Service (ENS) vulnerabilities.