NRDAX-T0071 - Ethash Verification Memory Exhaustion

Memory amplification · P2P and gossip · no bound · active · first seen 2026-07-09

provenance: Reproduced in NullRabbit's attack-reproduction pipeline

mechanism

CVE-2021-42219: go-ethereum v1.10.9 (and earlier pre-Merge ethash-verifying geth) - an unauthenticated remote peer floods a node with an excessive amount of block/header messages; to verify each block's PoW geth must hold the ethash cache for that block's epoch (number // 30000; ~16 MB+ each, generated in consensus/ethash/algorithm.go), so a flood whose announced block numbers span many distinct epochs forces many large cache allocations -> memory exhaustion (the cache for the claimed epoch is generated BEFORE the invalid mixHash/nonce is rejected, so a bogus PoW still triggers the cost). Network-triggered, availability-only (CVSS 7.5, AV:N/A:H). No vendor GHSA; the ethash PoW path was removed at The Merge (Sept 2022), so this is a pre-Merge class. Faithful known-class replication of the flood wire signature; the OOM impact is the CVE's, not reproduced against a live node.

live exposure

No exposure data. Slashr ↗ has no risk signal mapped to this technique yet — absence of data is not absence of exposure.

instances (1)

chain	primitive	fidelity	origin	reproducer (bundle)	source
ethereum	geth_ethash_memory_exhaustion_dos	lab	reverse-engineered-cve	geth_ethash_memory_exhaustion_dos	CVE-2021-42219 ↗

related (Memory amplification)

NRDAX-T0023 - Coalesced Packet Buffer Leak active NRDAX-T0025 - Compact Block Size Integer Overflow active NRDAX-T0038 - Count Underflow Header Serving Amplification active NRDAX-T0042 - Crypto Frame Reassembly Buffer Exhaustion active NRDAX-T0046 - Decompression Bomb Resource Exhaustion active NRDAX-T0059 - Duplicate Transport Parameter Memory Leak active NRDAX-T0061 - Duplicate Tx Mempool Index Desync active NRDAX-T0095 - GraphQL Alias Query Amplification active

cite

https://nrdax.com/techniques/NRDAX-T0071

plain

NRDAX Registry. Technique NRDAX-T0071.

bibtex

@misc{nrdax_NRDAX_T0071,
  title = {Ethash Verification Memory Exhaustion (NRDAX-T0071)},
  howpublished = {NRDAX Registry},
  url = {https://nrdax.com/techniques/NRDAX-T0071},
}

json (csl)

{
  "id": "nrdax-NRDAX-T0071",
  "type": "dataset",
  "title": "Ethash Verification Memory Exhaustion (NRDAX-T0071)",
  "URL": "https://nrdax.com/techniques/NRDAX-T0071",
  "publisher": "NRDAX Registry"
}

badge

[![NRDAX-T0071 in the NRDAX registry](https://nrdax.com/badge/NRDAX-T0071.svg)](https://nrdax.com/techniques/NRDAX-T0071-ethash-verification-memory-exhaustion)

use from the CLI

Retrieve or cite this technique from a script or the terminal with the NRDAX Python library & CLI.

Retrieve this technique

nrdax get NRDAX-T0071

Cite it (BibTeX)

nrdax cite NRDAX-T0071 --format bibtex

CLI guide → GitHub ↗