Researchers Disclose Clock Attack Vulnerability in Solana PoH

Researchers from USENIX Security disclosed a clock attack vulnerability in Solana's Proof of History (PoH) mechanism, which was privately reported to the development team in December 2025. The attack allows a malicious leader to manipulate the PoH logical clock to gain an advantage in transaction selection. Solana developers acknowledged the issue, noting that the probability of a severe exploit is low under current conditions.