Rethinking Assessments of Prompt Injection Attacks

Chi Cui, Yixin Wu, Michael Backes, Yang Zhang


Abstract
Prompt injection attacks are recognized as one of the primary risks faced by LLM-integrated applications in recent years. However, common evaluation frameworks remain insufficient, lacking comprehensiveness and real-world relevance. To bridge this gap, we revisit the common evaluation framework and conduct an extensive evaluation across eight different evaluation settings, including 37 real-world applications, 185 injected tasks, 21 attack instructions, and a total of 143,745 queries. The evaluation highlights several findings. For example, real-world applications are more vulnerable to prompt injection attacks compared to those used in research settings. While complex attack instructions are more sophisticated, they are less effective than simple attack instructions. We further conduct an assessment of both prompt-level and model-level defense mechanisms and highlight their limitations in real-world applications. By exploring more diverse scenarios across different dimensions, our framework provides a solid foundation for assessing vulnerabilities in LLM-integrated applications and evaluating the efficacy of defensive strategies.
Anthology ID:
2026.findings-acl.1191
Volume:
Findings of the Association for Computational Linguistics: ACL 2026
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
23773–23799
Language:
URL:
https://preview.aclanthology.org/ingest-acl/2026.findings-acl.1191/
DOI:
Bibkey:
Cite (ACL):
Chi Cui, Yixin Wu, Michael Backes, and Yang Zhang. 2026. Rethinking Assessments of Prompt Injection Attacks. In Findings of the Association for Computational Linguistics: ACL 2026, pages 23773–23799, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
Rethinking Assessments of Prompt Injection Attacks (Cui et al., Findings 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl/2026.findings-acl.1191.pdf
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