LeakageBench: Document-Level Leakage Risk for Redacting Personally Identifiable Information in Document Images

Vishnu Prasad Vijaya Kumar, Santhosh Venkatesh, Ivan P. Yamshchikov


Abstract
Real-world personally identifiable information (PII) redaction often operates on document images—scans, screenshots, and PDF renderings—where OCR errors, layout structure, and visual noise determine whether sensitive information is actually removed. Existing PII benchmarks are mostly text-centric and do not measure document-level redaction risk: a page remains unsafe if even one identifier is missed. We introduce LeakageBench, a challenge set of 500 document images with 11,954 GDPR-aligned PII annotations spanning direct identifiers, linkage keys, and contextual re-identification surfaces. We evaluate generic OCR pipelines, commercial and task-adapted OCR-dependent detectors, and OCR-free vision-language models using entity-level F1, group-wise leakage, and document-level leakage metrics. Code Interpreter raises GPT-5.5 localization F1 from 0.090 to 0.249, but critical page-level leakage remains 0.968. These results show that stronger detection and tool assistance improve localization without making most pages safe for release. LeakageBench provides a diagnostic benchmark for high-recall, spatially grounded PII redaction in document images.
Anthology ID:
2026.findings-emnlp.2350
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:
50519–50537
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2350/
DOI:
Bibkey:
Cite (ACL):
Vishnu Prasad Vijaya Kumar, Santhosh Venkatesh, and Ivan P. Yamshchikov. 2026. LeakageBench: Document-Level Leakage Risk for Redacting Personally Identifiable Information in Document Images. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 50519–50537, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
LeakageBench: Document-Level Leakage Risk for Redacting Personally Identifiable Information in Document Images (Kumar et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.2350.pdf