CVE-2026-104423: Zebra before 6.2.1 Denial of Service via Uncapped V6 Shielded Proof Verification
Zebra (zebrad) before 6.2.1 contains an asymmetric resource consumption vulnerability that allows unauthenticated peers to stall block verification by pushing V6 mempool transactions with invalid Halo2 proofs. Attackers can flood the shared unprioritized Halo2 verification queue with zero-fee transactions carrying zero-filled Orchard and Ironwood proofs, causing nodes to fall behind the chain tip.
Affected Software
Event History
Frequently Asked Questions
Who can exploit this issue?
Any unauthenticated peer able to submit V6 mempool transactions can exploit it. The attack does not require privileges, user interaction, or transaction fees.
What conditions are required for a node to be affected?
The node must run zebrad before 6.2.1 and process V6 mempool transactions containing invalid Halo2 proofs. The described attack uses zero-filled Orchard and Ironwood proofs to consume the shared unprioritized Halo2 verification queue.
What is the operational impact of exploitation?
An attacker can flood the verification queue, stall block verification, and cause affected nodes to fall behind the chain tip. The provided information describes an availability impact only, with no confidentiality or integrity impact stated.