Polygon patched several PoS security vulnerabilities through the Austin and Kyoto hard forks before publicly disclosing the fixes.The Austin fork closed two denial of service paths, including one that could let a malicious block producer crash peer nodes.The Kyoto fork fixed a flaw that could force Polygon’s validator set to perform costly processing from a single crafted transaction.Polygon said none of the vulnerabilities were exploited on mainnet, while both upgrades are now mandatory for node operators.