Synthetic is all you need: removing the auxiliary data assumption for membership inference attacks against synthetic data
On the map: LLM safety and security → Membership inference attacks
Abstract (arXiv)
Synthetic data is emerging as one of the most promising solutions to share individual-level data while safeguarding privacy. While membership inference attacks (MIAs), based on shadow modeling, have become the standard to evaluate the privacy of synthetic data, they currently assume the attacker to have access to an auxiliary dataset sampled from a similar distribution as the training dataset. This is often seen as a very strong assumption in practice, especially as the proposed main use cases for synthetic tabular data (e.g. medical data, financial transactions) are very specific and don't have any reference datasets directly available. We here show how this assumption can be removed, allowing for MIAs to be performed using only the synthetic data. Specifically, we developed three different scenarios: (S1) Black-box access to the generator, (S2) only access to the released synthetic dataset and (S3) a theoretical setup as upper bound for the attack performance using only synthetic data. Our results show that MIAs are still successful, across two real-world datasets and two synthetic data generators. These results show how the strong hypothesis made when auditing synthetic data releases - access to an auxiliary dataset - can be relaxed, making the attacks more realistic in practice.
Key facts. Cited by 18 papers in the map (data through 7 Oct 2026). Placed in Membership inference attacks, one of 12 directions in LLM safety and security. Builds on 13 of its 34 references that are in the map. First posted on arXiv 4 Jul 2023.
Builds on
13 of 34 references.
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Other references · 12
- 2016Membership Inference Attacks against Machine Learning Modelscited by 2,221
- 2019Modeling Tabular data using Conditional GANcited by 695
- 2018ML-Leaks: Model and Data Independent Membership Inference Attacks and Defenses on Machine Learning Modelscited by 475
- 2020Synthetic Data -- Anonymisation Groundhog Daycited by 105
- 2017Knock Knock, Who's There? Membership Inference on Aggregate Location Datacited by 63
- 2022TAPAS: a Toolbox for Adversarial Privacy Auditing of Synthetic Datacited by 56
- 2022A Unified Framework for Quantifying Privacy Risk in Synthetic Datacited by 45
- 2023Achilles' Heels: Vulnerable Record Identification in Synthetic Data Publishingcited by 28
- 2023A Linear Reconstruction Approach for Attribute Inference Attacks against Synthetic Datacited by 23
- 2022Understanding Real-world Threats to Deep Learning Models in Android Appscited by 15
- 2021Correlation inference attacks against machine learning modelscited by 7
- 2020Design of a Privacy-Preserving Data Platform for Collaboration Against Human Traffickingcited by 4
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Citing papers per year: 2023: 1; 2024: 4; 2025: 6; 2026: 7.
18 papers.
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- 2023The Inadequacy of Similarity-based Privacy Metrics: Privacy Attacks against "Truly Anonymous" Synthetic Datasetscited by 14
- 2025The DCR Delusion: Measuring the Privacy Risk of Synthetic Datacited by 11
- 2024Privacy Vulnerabilities in Marginals-based Synthetic Datacited by 10
- 2025Evaluating Differentially Private Generation of Domain-Specific Textcited by 5
- 2025Generating Synthetic Data with Formal Privacy Guarantees: State of the Art and the Road Aheadcited by 4
- 2025MIA-EPT: Membership Inference Attack via Error Prediction for Tabular Datacited by 4
- 2024A Zero Auxiliary Knowledge Membership Inference Attack on Aggregate Location Datacited by 3
- 2025Synthetic Data Can Mislead Evaluations: Membership Inference as Machine Text Detectioncited by 3
- 2024VFLGAN: Vertical Federated Learning-based Generative Adversarial Network for Vertically Partitioned Data Publicationcited by 1
- 2025Biologically-Informed Hybrid Membership Inference Attacks on Generative Genomic Modelscited by 1
- 2026Rethinking Anonymity Claims in Synthetic Data Generation: A Model-Centric Privacy Attack Perspectivecited by 1
- 2026A Dual Perspective on Synthetic Trajectory Generators: Utility Framework and Privacy Vulnerabilitiescited by 1
6 more
- 2024Lost in the Averages: A New Specific Setup to Evaluate Membership Inference Attacks Against Machine Learning Modelscited by 0
- 2026Quantifying Membership Disclosure Risk for Tabular Synthetic Data Using Kernel Density Estimatorscited by 0
- 2026Automated Membership Inference Attacks (AutoMIA): Discovering MIA Signal Computations using LLM Agentscited by 0
- 2026diffGHOST: Diffusion based Generative Hedged Oblivious Synthetic Trajectoriescited by 0
- 2026ReMIA: a Powerful and Efficient Alternative to Membership Inference Attacks against Synthetic Data Generatorscited by 0
- 2026It does what it says on the tin: safe synthetic data from coarsened marginscited by 0
- 2026It does what it says on the tin: safe synthetic data from coarsened margins1 Jun 2026
- 2026ReMIA: a Powerful and Efficient Alternative to Membership Inference Attacks against Synthetic Data Generators14 May 2026
- 2026diffGHOST: Diffusion based Generative Hedged Oblivious Synthetic Trajectories11 May 2026
- 2026A Dual Perspective on Synthetic Trajectory Generators: Utility Framework and Privacy Vulnerabilities21 Apr 2026
- 2026Automated Membership Inference Attacks (AutoMIA): Discovering MIA Signal Computations using LLM Agents19 Mar 2026
- 2026Quantifying Membership Disclosure Risk for Tabular Synthetic Data Using Kernel Density Estimators11 Mar 2026
- 2026Rethinking Anonymity Claims in Synthetic Data Generation: A Model-Centric Privacy Attack Perspective30 Jan 2026
- 2025Biologically-Informed Hybrid Membership Inference Attacks on Generative Genomic Models10 Nov 2025
- 2025MIA-EPT: Membership Inference Attack via Error Prediction for Tabular Data16 Sep 2025
- 2025Evaluating Differentially Private Generation of Domain-Specific Text28 Aug 2025
- 2025The DCR Delusion: Measuring the Privacy Risk of Synthetic Data2 May 2025
- 2025Generating Synthetic Data with Formal Privacy Guarantees: State of the Art and the Road Ahead26 Mar 2025
6 more
- 2025Synthetic Data Can Mislead Evaluations: Membership Inference as Machine Text Detection20 Jan 2025
- 2024Privacy Vulnerabilities in Marginals-based Synthetic Data7 Oct 2024
- 2024A Zero Auxiliary Knowledge Membership Inference Attack on Aggregate Location Data26 Jun 2024
- 2024Lost in the Averages: A New Specific Setup to Evaluate Membership Inference Attacks Against Machine Learning Models24 May 2024
- 2024VFLGAN: Vertical Federated Learning-based Generative Adversarial Network for Vertically Partitioned Data Publication15 Apr 2024
- 2023The Inadequacy of Similarity-based Privacy Metrics: Privacy Attacks against "Truly Anonymous" Synthetic Datasets8 Dec 2023
- 2025The DCR Delusion: Measuring the Privacy Risk of Synthetic Datacited by 11
- 2024A Zero Auxiliary Knowledge Membership Inference Attack on Aggregate Location Datacited by 3
- 2025Biologically-Informed Hybrid Membership Inference Attacks on Generative Genomic Modelscited by 1
- 2024Lost in the Averages: A New Specific Setup to Evaluate Membership Inference Attacks Against Machine Learning Modelscited by 0
- 2026ReMIA: a Powerful and Efficient Alternative to Membership Inference Attacks against Synthetic Data Generatorscited by 0
- 2026ReMIA: a Powerful and Efficient Alternative to Membership Inference Attacks against Synthetic Data Generators14 May 2026
- 2025Biologically-Informed Hybrid Membership Inference Attacks on Generative Genomic Models10 Nov 2025
- 2025The DCR Delusion: Measuring the Privacy Risk of Synthetic Data2 May 2025
- 2024A Zero Auxiliary Knowledge Membership Inference Attack on Aggregate Location Data26 Jun 2024
- 2024Lost in the Averages: A New Specific Setup to Evaluate Membership Inference Attacks Against Machine Learning Models24 May 2024
- 2023The Inadequacy of Similarity-based Privacy Metrics: Privacy Attacks against "Truly Anonymous" Synthetic Datasetscited by 14
- 2024Privacy Vulnerabilities in Marginals-based Synthetic Datacited by 10
- 2025Evaluating Differentially Private Generation of Domain-Specific Textcited by 5
- 2025Generating Synthetic Data with Formal Privacy Guarantees: State of the Art and the Road Aheadcited by 4
- 2024VFLGAN: Vertical Federated Learning-based Generative Adversarial Network for Vertically Partitioned Data Publicationcited by 1
- 2026Rethinking Anonymity Claims in Synthetic Data Generation: A Model-Centric Privacy Attack Perspectivecited by 1
- 2026A Dual Perspective on Synthetic Trajectory Generators: Utility Framework and Privacy Vulnerabilitiescited by 1
- 2026Quantifying Membership Disclosure Risk for Tabular Synthetic Data Using Kernel Density Estimatorscited by 0
- 2026It does what it says on the tin: safe synthetic data from coarsened marginscited by 0
- 2026It does what it says on the tin: safe synthetic data from coarsened margins1 Jun 2026
- 2026A Dual Perspective on Synthetic Trajectory Generators: Utility Framework and Privacy Vulnerabilities21 Apr 2026
- 2026Quantifying Membership Disclosure Risk for Tabular Synthetic Data Using Kernel Density Estimators11 Mar 2026
- 2026Rethinking Anonymity Claims in Synthetic Data Generation: A Model-Centric Privacy Attack Perspective30 Jan 2026
- 2025Evaluating Differentially Private Generation of Domain-Specific Text28 Aug 2025
- 2025Generating Synthetic Data with Formal Privacy Guarantees: State of the Art and the Road Ahead26 Mar 2025
- 2024Privacy Vulnerabilities in Marginals-based Synthetic Data7 Oct 2024
- 2024VFLGAN: Vertical Federated Learning-based Generative Adversarial Network for Vertically Partitioned Data Publication15 Apr 2024
- 2023The Inadequacy of Similarity-based Privacy Metrics: Privacy Attacks against "Truly Anonymous" Synthetic Datasets8 Dec 2023