CVE-2026-104423: Asymmetric Resource Consumption (Amplification) in ZcashFoundation zebra
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.
AI Analysis
Technical Summary
CVE-2026-104423 describes an asymmetric resource consumption vulnerability in ZcashFoundation's Zebra client (zebrad) prior to version 6.2.1. Attackers can exploit this by pushing V6 mempool transactions with invalid Halo2 proofs, specifically zero-filled Orchard and Ironwood proofs, into the shared unprioritized Halo2 verification queue. This causes the queue to be flooded with zero-fee transactions, stalling block verification and causing nodes to fall behind the chain tip.
Potential Impact
The vulnerability allows unauthenticated attackers to degrade node performance by stalling block verification, potentially causing nodes to lag behind the blockchain tip. This can disrupt normal node operation and network synchronization but does not involve privilege escalation or data compromise.
Mitigation Recommendations
A fix is available in Zebra version 6.2.1. Users should upgrade to version 6.2.1 or later to remediate this vulnerability. No additional mitigation guidance is provided or necessary beyond applying the official fix.
CVE-2026-104423: Asymmetric Resource Consumption (Amplification) in ZcashFoundation zebra
Description
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.
CVSS v4.0
Score 8.7high
Affected software
ZcashFoundation
zebra
pkg:github/zcashfoundation/zebraRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-104423 describes an asymmetric resource consumption vulnerability in ZcashFoundation's Zebra client (zebrad) prior to version 6.2.1. Attackers can exploit this by pushing V6 mempool transactions with invalid Halo2 proofs, specifically zero-filled Orchard and Ironwood proofs, into the shared unprioritized Halo2 verification queue. This causes the queue to be flooded with zero-fee transactions, stalling block verification and causing nodes to fall behind the chain tip.
Potential Impact
The vulnerability allows unauthenticated attackers to degrade node performance by stalling block verification, potentially causing nodes to lag behind the blockchain tip. This can disrupt normal node operation and network synchronization but does not involve privilege escalation or data compromise.
Mitigation Recommendations
A fix is available in Zebra version 6.2.1. Users should upgrade to version 6.2.1 or later to remediate this vulnerability. No additional mitigation guidance is provided or necessary beyond applying the official fix.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-10-02T00:46:23.830Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6abf99afa43b0b3b89b26902
Added to database: 10/02/2026, 11:46:55 UTC
Last enriched: 10/02/2026, 12:16:23 UTC
Last updated: 10/03/2026, 03:10:01 UTC
Views: 12
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