Zebra Blockchain Verification Issues

Consensus-breaking cache logic error in Zcash Zebra node software (all versions <4.3.1) allows malicious miners to partition the network by mining blocks containing height-invalid transactions. By submitting a transaction valid at height H+1 but invalid at H+2, then mining it into block H+2 and submitting that block before H+1, attackers trigger cached verification bypass-vulnerable Zebra nodes accept the invalid block while honest nodes reject it, creating a consensus split. This enables double-spend attacks against isolated nodes. EPSS data unavailable; not in CISA KEV. Classified as CWE-1025 (comparison logic error). Fixed in Zebra 4.3.1 by removing the risky cache optimization entirely.

Zebra cryptocurrency node prior to version 4.3.1 allocates excessive memory (up to 233,016 addresses) when deserializing addr/addrv2 protocol messages, even though the specification limits messages to 1,000 addresses. An attacker can trigger out-of-memory crashes by sending multiple oversized address messages over different connections. This is a network-accessible denial of service vulnerability affecting all Zebra versions before 4.3.1, with no public exploit code identified but straightforward to execute given the protocol specification.