NRDAX-T0411 - SIGHASH_SINGLE Missing-Output Validation Gap

consensus_abuse · active · first seen 2026-07-20

provenance: Reproduced in NullRabbit's attack-reproduction pipeline

mechanism

The node's transaction sighash routine fails to reject SIGHASH_SINGLE inputs whose index is >= the number of outputs; instead of throwing (the spec-mandated behavior), it silently substitutes an empty output set when computing the signature digest. An attacker crafts a transparent transaction with more inputs than outputs and signs the offending input with SIGHASH_SINGLE at an out-of-range index against this empty-set digest, producing a signature the defective node validates and accepts into its mempool/block template while spec-compliant nodes reject it. This divergence yields a direct block-validity consensus split between vulnerable and correct implementations.

instances (1)

chain	primitive	fidelity	origin	reproducer (bundle)	source
zcash	zebra_sighash_single_missing_output	lab	reverse-engineered-cve	zebra_sighash_single_missing_output	-

related (consensus_abuse)

NRDAX-T0024 - Compact Block FillBlock Duplicate Crash active NRDAX-T0056 - Duplicate Input Validation-Bypass Crash active NRDAX-T0143 - Malformed Field Gossip Before Validation active NRDAX-T0165 - Missing Zero-Guard Divide-By-Zero Halt active NRDAX-T0202 - Peer Timestamp Skew Manipulation active NRDAX-T0207 - Pre-Verify Gossip Flood active NRDAX-T0211 - Premature Processing Index-Out-Of-Range Panic active NRDAX-T0298 - Timestamp Integer Overflow Netsplit active

cite

https://nrdax.com/techniques/NRDAX-T0411

plain

NRDAX Registry. Technique NRDAX-T0411.

bibtex

@misc{nrdax_NRDAX_T0411,
  title = {SIGHASH_SINGLE Missing-Output Validation Gap (NRDAX-T0411)},
  howpublished = {NRDAX Registry},
  url = {https://nrdax.com/techniques/NRDAX-T0411},
}

json (csl)

{
  "id": "nrdax-NRDAX-T0411",
  "type": "dataset",
  "title": "SIGHASH_SINGLE Missing-Output Validation Gap (NRDAX-T0411)",
  "URL": "https://nrdax.com/techniques/NRDAX-T0411",
  "publisher": "NRDAX Registry"
}

badge

[![NRDAX-T0411 in the NRDAX registry](https://nrdax.com/badge/NRDAX-T0411.svg)](https://nrdax.com/techniques/NRDAX-T0411-sighash-single-missing-output-validation-gap)

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-T0411

Cite it (BibTeX)

nrdax cite NRDAX-T0411 --format bibtex

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