CVE-2026-40880

Name of the Vulnerable Software and Affected Versions Zebra versions prior to 4.3.1

Description A logic error in the transaction verification cache allows a malicious miner to induce a consensus split. The issue stems from a performance optimization that skips transaction validation if the transaction was previously accepted into the mempool. This mechanism fails to account for height-dependent validity, such as expiry heights, lock times, or network upgrades. An attacker could submit a transaction valid for height H+1 but invalid for H+2, then mine it into a block at height H+2. Vulnerable nodes may accept the invalid block, leading to a chain fork and network partitioning from the rest of the Zcash network.

Recommendations Update to Zebra version 4.3.1.