CVE-2023-28431

CVE-2023-28431 is a denial-of-service vulnerability affecting Frontier, an Ethereum compatibility layer for Substrate. The vulnerability stems from a gas cost discrepancy in Frontier's modexp precompile, where even modulus calculations are significantly slower than odd modulus calculations due to the underlying num-bigint library. This allows an attacker to trigger resource exhaustion by forcing inefficient computations. Rated 7.5 HIGH on CVSS, it has a network attack vector and low attack complexity, potentially leading to a full denial of service. There is currently no known active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.