GHSA-5h3r-fpmj-483w: Zebra 4.5.0 before 7.0.0 Honest Peer Ban via Mempool Lock-Time Scoring
ZcashFoundation Zebra from 4.5.0 before 7.0.0 contains a protection mechanism failure that bans honest peers by scoring mempool lock-time rejections at the ban threshold. Attackers can broadcast transactions locked until the current height right after each block, causing lagging nodes to ban honest relaying peers for 24 hours or until restart.
Event History
Frequently Asked Questions
Which nodes are exposed to this issue?
Zebra versions from 4.5.0 up to, but not including, 7.0.0 are affected. Nodes that relay transactions from peers can be impacted when they are lagging behind the current chain height.
What does an attacker need to do to trigger peer bans?
An attacker can broadcast transactions locked until the current height immediately after each block. This can cause a lagging node to score honest peers that relay those transactions at the ban threshold.
What is the operational impact of a successful attack?
Affected nodes may ban honest relaying peers for 24 hours. The ban also ends if the node is restarted.