Trust Cascade through Provenance Erasure: How Multi-Agent Delegation Breaks Single-Agent Safety

Yuxin Zhou, Xiao Ding, Tianle Chang, Ye He, Wenbin Zhang, ShangZhan Li, Yijia Meng, Wenyu Zang, Bibo Cai, Qi Shi


Abstract
Multi-agent LLM systems delegate through natural language, creating trust boundaries that single-agent safety hierarchies were not designed to preserve. We identify provenance erasure as a multi-agent safety failure mechanism: even in the minimal two-agent case, delegation strips trust metadata—98% of format markers, 100% of authority entities, and 44% of source attribution across 460 pairs—while often preserving the actionable payload. This lossy transform enables Trust Cascade, amplifying system-channel attacks from 0% to 33–63% cascade ASR across eight open-weight models; a delegation-as-user control isolates channel trust escalation rather than content reformulation. Because the failure occurs at the delegation boundary, we propose the Trust Boundary Auditor (TBA), a zero-inference provenance diagnostic achieving 86–100% conditional detection with 0% false positives across four domains. Training, scale, and closed-source evaluations show that stronger models can interrupt different cascade stages but do not remove the boundary problem, suggesting that multi-agent safety requires delegation gating plus provenance auditing.
Anthology ID:
2026.emnlp-main.1005
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:
23130–23148
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1005/
DOI:
Bibkey:
Cite (ACL):
Yuxin Zhou, Xiao Ding, Tianle Chang, Ye He, Wenbin Zhang, ShangZhan Li, Yijia Meng, Wenyu Zang, Bibo Cai, and Qi Shi. 2026. Trust Cascade through Provenance Erasure: How Multi-Agent Delegation Breaks Single-Agent Safety. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 23130–23148, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Trust Cascade through Provenance Erasure: How Multi-Agent Delegation Breaks Single-Agent Safety (Zhou et al., EMNLP 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.emnlp-main.1005.pdf