AIKIDO-2026-10377

TL;DR

In XChaCha::decrypt_bytes_with_associated_data, malformed ciphertext was passed to EncryptedData::read_from_bytes and the result was unwrapped; invalid input causes a panic and denial of service. Deserialization of untrusted data for MMR, MerkleStore, and crypto types could previously trigger OOMs or panics; the release adds budgeted reading and fuzz-hardened validation. NodeIndex::to_scalar_index() used a left shift by depth (up to 64) without checks, causing undefined behavior at depth 64 (panic in debug, wrong value in release). The patch replaces the unwrap with proper error propagation, switches untrusted deserialization to read_from_bytes_with_budget(), and fixes the overflow by using checked arithmetic and returning Result.