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Mon, 01 Jan 0001 00:00:00 +0000

Zcash Zebra GHSA-8gxx-hc65-vv82 writeup

Thu, 08 Oct 2026 00:00:00 +0000

In July, I reported a chain-stall vulnerability in Zebra, a widely used Zcash node client — GHSA-8gxx-hc65-vv82. In this article, I explain the root cause and the patch.

Summary

In Zebra, if a block fails contextual validation, its hash is recorded in parent_error_map. When the block write task receives a new block, Zebra rejects it if its parent hash is in parent_error_map. An entry in the map isn’t evicted until the size of the map exceeds PARENT_ERROR_MAP_LIMIT (= 2,000) because no other code path removes entries from the map.

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Zcash Zebra GHSA-8gxx-hc65-vv82 writeup

Summary