An integer overflow in Nethermind Juno before v.12.05 within the Sierra bytecode decompression logic within the "cairo-lang-starknet-classes" library could allow remote attackers to trigger an infinite loop (and high CPU usage) by submitting a malicious Declare v2/v3 transaction. This results in a denial-of-service condition for affected Starknet full-node implementations.
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.