@inproceedings{shahariar-etal-2026-pii,
title = "{PII}-{V}is{B}ench: Evaluating Personally Identifiable Information Safety in Vision Language Models Along a Continuum of Visibility",
author = "Shahariar, G M and
Al Nazi, Zabir and
Bhuiyan, Md Olid Hasan and
Shi, Zhouxing",
editor = "Liakata, Maria and
Moreira, Viviane P. and
Zhang, Jiajun and
Jurgens, David",
booktitle = "Findings of the {A}ssociation for {C}omputational {L}inguistics: {ACL} 2026",
month = jul,
year = "2026",
address = "San Diego, California, United States",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.findings-acl.501/",
pages = "10294--10316",
ISBN = "979-8-89176-395-1",
abstract = "Vision Language Models (VLMs) are increasingly integrated into privacy-critical domains, yet existing evaluations of personally identifiable information (PII) leakage largely treat privacy as a static extraction task and ignore how a subject{'}s online presence{---}the volume of their data available online{---}influences privacy alignment. We introduce **PII-VisBench**, a novel benchmark containing 4,000 unique probes designed to evaluate VLM safety through the *continuum of online presence*. The benchmark stratifies 200 subjects into four visibility categories: *high, medium, low,* and *zero*{---}based on the extent and nature of their information available online. We evaluate 18 open-source VLMs (0.3B{--}32B) based on two key metrics: percentage of PII probing queries refused (*Refusal Rate*) and the fraction of non-refusal responses flagged for containing PII (*Conditional PII Disclosure Rate*). Across models, we observe a consistent pattern: refusals increase and PII disclosures decrease (9.10{\%} high $\rightarrow$ 5.34{\%} low) as subject visibility drops. We identify that models are more likely to disclose PII for high-visibility subjects, alongside substantial model-family heterogeneity and PII-type disparities. Finally, paraphrasing and jailbreak-style prompts expose attack- and model-dependent failures, motivating visibility-aware safety evaluation and training interventions."
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<abstract>Vision Language Models (VLMs) are increasingly integrated into privacy-critical domains, yet existing evaluations of personally identifiable information (PII) leakage largely treat privacy as a static extraction task and ignore how a subject’s online presence—the volume of their data available online—influences privacy alignment. We introduce **PII-VisBench**, a novel benchmark containing 4,000 unique probes designed to evaluate VLM safety through the *continuum of online presence*. The benchmark stratifies 200 subjects into four visibility categories: *high, medium, low,* and *zero*—based on the extent and nature of their information available online. We evaluate 18 open-source VLMs (0.3B–32B) based on two key metrics: percentage of PII probing queries refused (*Refusal Rate*) and the fraction of non-refusal responses flagged for containing PII (*Conditional PII Disclosure Rate*). Across models, we observe a consistent pattern: refusals increase and PII disclosures decrease (9.10% high \rightarrow 5.34% low) as subject visibility drops. We identify that models are more likely to disclose PII for high-visibility subjects, alongside substantial model-family heterogeneity and PII-type disparities. Finally, paraphrasing and jailbreak-style prompts expose attack- and model-dependent failures, motivating visibility-aware safety evaluation and training interventions.</abstract>
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%0 Conference Proceedings
%T PII-VisBench: Evaluating Personally Identifiable Information Safety in Vision Language Models Along a Continuum of Visibility
%A Shahariar, G. M.
%A Al Nazi, Zabir
%A Bhuiyan, Md Olid Hasan
%A Shi, Zhouxing
%Y Liakata, Maria
%Y Moreira, Viviane P.
%Y Zhang, Jiajun
%Y Jurgens, David
%S Findings of the Association for Computational Linguistics: ACL 2026
%D 2026
%8 July
%I Association for Computational Linguistics
%C San Diego, California, United States
%@ 979-8-89176-395-1
%F shahariar-etal-2026-pii
%X Vision Language Models (VLMs) are increasingly integrated into privacy-critical domains, yet existing evaluations of personally identifiable information (PII) leakage largely treat privacy as a static extraction task and ignore how a subject’s online presence—the volume of their data available online—influences privacy alignment. We introduce **PII-VisBench**, a novel benchmark containing 4,000 unique probes designed to evaluate VLM safety through the *continuum of online presence*. The benchmark stratifies 200 subjects into four visibility categories: *high, medium, low,* and *zero*—based on the extent and nature of their information available online. We evaluate 18 open-source VLMs (0.3B–32B) based on two key metrics: percentage of PII probing queries refused (*Refusal Rate*) and the fraction of non-refusal responses flagged for containing PII (*Conditional PII Disclosure Rate*). Across models, we observe a consistent pattern: refusals increase and PII disclosures decrease (9.10% high \rightarrow 5.34% low) as subject visibility drops. We identify that models are more likely to disclose PII for high-visibility subjects, alongside substantial model-family heterogeneity and PII-type disparities. Finally, paraphrasing and jailbreak-style prompts expose attack- and model-dependent failures, motivating visibility-aware safety evaluation and training interventions.
%U https://aclanthology.org/2026.findings-acl.501/
%P 10294-10316
Markdown (Informal)
[PII-VisBench: Evaluating Personally Identifiable Information Safety in Vision Language Models Along a Continuum of Visibility](https://aclanthology.org/2026.findings-acl.501/) (Shahariar et al., Findings 2026)
ACL