Assessing and Mitigating Data Memorization Risks in Fine-Tuned Large Language Models

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Hauptverfasser: Ramakrishnan, Badrinath, Balaji, Akshaya
Format: Preprint
Veröffentlicht: 2025
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author Ramakrishnan, Badrinath
Balaji, Akshaya
author_facet Ramakrishnan, Badrinath
Balaji, Akshaya
contents Large Language Models (LLMs) have demonstrated remarkable capabilities across diverse natural language processing tasks, but their tendency to memorize training data poses significant privacy risks, particularly during fine-tuning processes. This paper presents a comprehensive empirical analysis of data memorization in fine-tuned LLMs and introduces a novel multi-layered privacy protection framework. Through controlled experiments on modern LLM architectures including GPT-2, Phi-3, and Gemma-2, we demonstrate that fine-tuning with repeated sensitive data increases privacy leakage rates from baseline levels of 0-5% to 60-75%, representing a 64.2% average increase across tested models. We propose and rigorously evaluate four complementary privacy protection methods: semantic data deduplication, differential privacy during generation, entropy-based filtering, and pattern-based content filtering. Our experimental results show that these techniques can reduce data leakage to 0% while maintaining 94.7% of original model utility.
format Preprint
id arxiv_https___arxiv_org_abs_2508_14062
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Assessing and Mitigating Data Memorization Risks in Fine-Tuned Large Language Models
Ramakrishnan, Badrinath
Balaji, Akshaya
Computation and Language
Artificial Intelligence
Large Language Models (LLMs) have demonstrated remarkable capabilities across diverse natural language processing tasks, but their tendency to memorize training data poses significant privacy risks, particularly during fine-tuning processes. This paper presents a comprehensive empirical analysis of data memorization in fine-tuned LLMs and introduces a novel multi-layered privacy protection framework. Through controlled experiments on modern LLM architectures including GPT-2, Phi-3, and Gemma-2, we demonstrate that fine-tuning with repeated sensitive data increases privacy leakage rates from baseline levels of 0-5% to 60-75%, representing a 64.2% average increase across tested models. We propose and rigorously evaluate four complementary privacy protection methods: semantic data deduplication, differential privacy during generation, entropy-based filtering, and pattern-based content filtering. Our experimental results show that these techniques can reduce data leakage to 0% while maintaining 94.7% of original model utility.
title Assessing and Mitigating Data Memorization Risks in Fine-Tuned Large Language Models
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2508.14062