Polygon Discloses PoS Vulnerabilities Patched in Austin and Kyoto Hard Forks

Polygon Labs has disclosed several previously unreported security vulnerabilities in its proof-of-stake network, revealing that fixes were deployed through two coordinated hard forks before the details were made public. The company stated that none of the flaws were exploited on mainnet and that the upgrades are now mandatory for all node operators to maintain consensus. The vulnerabilities, which affected the network's Bor execution client and Heimdall consensus client, were patched through the Austin and Kyoto hard forks. Polygon's Validators Support Team disclosed the fixes in a forum post on August 27, 2026, after both upgrades had already been tested and activated on the mainnet.