Evidence Laundering: Deep Research Agents Mistake Correlated Sources for Independent Evidence

Ruihua Zhou, Hao Huang, Yijie Zheng, JiaTang Luo, Yunpeng Li, Yuling Liu, Dan Du


Abstract
Deep research agents often rely on agreement among retrieved documents when deciding whether a claim is reliable. This heuristic breaks when the agreeing documents are not independent: several independent reports can support a claim, but several copies of the same false claim should not. We study evidence laundering, a content-only attack that publishes one false claim across paraphrased pages that appear to provide support from multiple sources. We evaluate this failure with deterministic matched corpora that present the same false claim and supporting propositions as a single source, a paraphrased correlated cluster, or an apparent independence control, with matched retrieval exposure. Experiments show that agents often assign laundered clusters credence comparable to the apparent independence control and become more willing to publish the false claim. Within the matched evaluation, a structural provenance gate substantially reduces this failure, suggesting that source independence modeling should precede answer synthesis.
Anthology ID:
2026.emnlp-main.509
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
11682–11693
Language:
URL:
https://aclanthology.org/2026.emnlp-main.509/
DOI:
Bibkey:
Cite (ACL):
Ruihua Zhou, Hao Huang, Yijie Zheng, JiaTang Luo, Yunpeng Li, Yuling Liu, and Dan Du. 2026. Evidence Laundering: Deep Research Agents Mistake Correlated Sources for Independent Evidence. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 11682–11693, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Evidence Laundering: Deep Research Agents Mistake Correlated Sources for Independent Evidence (Zhou et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.509.pdf