Towards Robust Retrieval-Augmented Generation via Reliability-Aware Adaptive Evidence Selection

Minkyu Che, Jihwan Oh, Jeonghwan Choi, Jeesu Jung, Hwanjun Song


Abstract
Retrieval-augmented generation (RAG) is increasingly deployed on unverified corpora, where an adversary can inject poisoned documents to steer the model toward an attacker-specified answer. Existing defenses rely on auxiliary heuristics and break down once their assumptions about the attack type or poisoning level are violated. We propose SAFER-RAG, a defense that derives its reliability signal from the adversarial objective itself. Since poisoned documents are explicitly optimized to rank highly for the target query, they remain anchored at top ranks under semantically equivalent rewrites, while clean documents shift naturally. SAFER-RAG captures this rank-stability gap through spectral analysis, partitions retrieved chunks into Safe and Unsafe Sets, and adaptively selects evidence under a safe-first strategy that avoids over-filtering useful evidence on clean or lightly poisoned corpora. Across three QA benchmarks, three attack types, and four poisoning levels, SAFER-RAG consistently achieves the highest accuracy and the lowest attack success rate. The code will be released upon acceptance.
Anthology ID:
2026.findings-emnlp.2302
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
49353–49374
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2302/
DOI:
10.18653/2026.findings-emnlp.2302
Bibkey:
Cite (ACL):
Minkyu Che, Jihwan Oh, Jeonghwan Choi, Jeesu Jung, and Hwanjun Song. 2026. Towards Robust Retrieval-Augmented Generation via Reliability-Aware Adaptive Evidence Selection. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 49353–49374, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Towards Robust Retrieval-Augmented Generation via Reliability-Aware Adaptive Evidence Selection (Che et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.2302.pdf