The read_getblocks and read_getheaders codec paths accepted block locator vectors up to approximately 65,535 entries (the generic TrustedPreallocate ceiling derived from MAX_PROTOCOL_MESSAGE_LEN), rather than the protocol-specification limit of 101 entries (matching zcashd's MAX_LOCATOR_SZ). Each entry in the locator vector triggers a per-hash chain lookup (HashMap::contains_key + RocksDB::contains_hash) in find_chain_intersection on a tokio blocking-pool thread. A single maximally-sized getblocks message occupies one blocking-pool thread for approximately 10–65ms. Under sustained load from …
Several inbound deserialization paths in Zebra allocated buffers sized against generic transport or block-size ceilings before the tighter protocol or consensus limits were enforced. An unauthenticated or post-handshake peer could therefore force the node to preallocate and parse for orders of magnitude more data than the protocol intended, across headers messages, equihash solutions in block headers, Sapling spend vectors in V5/V4 transactions, and coinbase script bytes in blocks.
Orchard transactions contain a rk field which is a randomized validating key and also an elliptic curve point. The Zcash specification allows the field to be the identity (a "zero" value), however, the orchard crate which is used to verify Orchard proofs would panic when fed a rk with the identity value. Thus an attacker could send a crafted transaction that would make a Zebra node crash.
Orchard transactions contain a rk field which is a randomized validating key and also an elliptic curve point. The Zcash specification allows the field to be the identity (a "zero" value), however, the orchard crate which is used to verify Orchard proofs would panic when fed a rk with the identity value. Thus an attacker could send a crafted transaction that would make a Zebra node crash.
A vulnerability in Zebra's transaction processing logic allows a remote, unauthenticated attacker to cause a Zebra node to panic (crash). This is triggered by sending a specially crafted V5 transaction that passes initial deserialization but fails during transaction ID calculation.