Intel

AIKIDO-2026-219573

zebrad is vulnerable to Denial of Service (DoS)

Denial of Service (DoS)GHSA-x93j-mj2f-q338 Published Jul 29, 2026

53

Medium Risk

This Affects:

RUSTzebrad
0.0.1 - 6.2.0
Fixed in 6.2.1
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TL;DR

When Zebra sends a semantically verified block to the write task it records the block hash in an in-memory sent-hash set to avoid queueing it twice. If contextual verification rejects the block the hash was drained on the commit path but not on the block-known lookup path, so a stale rejected entry made that lookup report an honest block as already present. A peer can get a poisoned block sharing a canonical block's header hash rejected, after which the node skips downloading the honest body and lags one block behind the tip until unrelated activity or a restart clears the entry. The fix drains pending rejected hashes before the block-known lookup checks the set.

Who does this affect?

You are affected if you are using a version that falls within the vulnerable range and your node accepts inbound peer-to-peer connections.

Background info

zebrad is vulnerable to Denial of Service (DoS) in versions 0.0.1 - 6.2.0.

How to fix this

Upgrade the zebrad library to the patch version.

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