Undesirable Memorization in Large Language Models: A Survey
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Abstract (arXiv)
While recent research increasingly showcases the remarkable capabilities of Large Language Models (LLMs), it is equally crucial to examine their associated risks. Among these, privacy and security vulnerabilities are particularly concerning, posing significant ethical and legal challenges. At the heart of these vulnerabilities stands memorization, which refers to a model's tendency to store and reproduce phrases from its training data. This phenomenon has been shown to be a fundamental source to various privacy and security attacks against LLMs. In this paper, we provide a taxonomy of the literature on LLM memorization, exploring it across three dimensions: granularity, retrievability, and desirability. Next, we discuss the metrics and methods used to quantify memorization, followed by an analysis of the causes and factors that contribute to memorization phenomenon. We then explore strategies that are used so far to mitigate the undesirable aspects of this phenomenon. We conclude our survey by identifying potential research topics for the near future, including methods to balance privacy and performance, and the analysis of memorization in specific LLM contexts such as conversational agents, retrieval-augmented generation, and diffusion language models. Given the rapid research pace in this field, we also maintain a dedicated repository of the references discussed in this survey which will be regularly updated to reflect the latest developments.
Key facts. Cited by 29 papers in the map (data through 7 Oct 2026). Builds on 117 of its 182 references that are in the map. First posted on arXiv 3 Oct 2024.
Builds on
117 of 182 references.
References · 117
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50 most cited of 117 All 117 (JSON)
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Citing papers per year: 2025: 18; 2026: 11.
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- 2025A Survey of Reinforcement Learning for Large Reasoning Modelscited by 175
- 2025R.R.: Unveiling LLM Training Privacy through Recollection and Rankingcited by 10
- 2025The Landscape of Memorization in LLMs: Mechanisms, Measurement, and Mitigationcited by 9
- 2025Mitigating Memorization in LLMs using Activation Steeringcited by 7
- 2025Extracting alignment data in open modelscited by 7
- 2025Trustworthy Machine Learning via Memorization and the Granular Long-Tail: A Survey on Interactions, Tradeoffs, and Beyondcited by 6
- 2025Rote Learning Considered Useful: Generalizing over Memorized Data in LLMscited by 5
- 2025Memorization in Large Language Models in Medicine: Prevalence, Characteristics, and Implicationscited by 5
- 2025KnowRL: Teaching Language Models to Know What They Knowcited by 5
- 2026A Survey on Evaluating Quality and Trustworthiness in LLM-Generated Datacited by 5
- 2026Membership Inference Attacks Against Fine-tuned Diffusion Language Modelscited by 5
- 2026Reward Modeling for Reinforcement Learning-Based LLM Reasoning: Design, Challenges, and Evaluationcited by 5
17 more
- 2025Watch Out Your Album! On the Inadvertent Privacy Memorization in Multi-Modal Large Language Modelscited by 3
- 2025Factored Agents: Decoupling In-Context Learning and Memorization for Robust Tool Usecited by 3
- 2025Beyond Public Access in LLM Pre-Training Datacited by 3
- 2025Mirage of Mastery: Memorization Tricks LLMs into Artificially Inflated Self-Knowledgecited by 2
- 2026GR-SAP: Generative Replay for Safety Alignment Preservation during Fine-Tuningcited by 2
- 2025Rethinking Memorization Measures and their Implications in Large Language Modelscited by 1
- 2025Memorization neq Understanding: Do Large Language Models Have the Ability of Scenario Cognition?cited by 1
- 2025We Are All Creators: Generative AI, Collective Knowledge, and the Path Towards Human-AI Synergycited by 0
- 2025Comparing Reconstruction Attacks on Pretrained Versus Full Fine-tuned Large Language Model Embeddings on Homo Sapiens Splice Sites Genomic Datacited by 0
- 2025Randomized Masked Finetuning: An Efficient Way to Mitigate Memorization of PIIs in LLMscited by 0
- 2026Operationalising the Right to be Forgotten in LLMs: A Lightweight Sequential Unlearning Framework for Privacy-Aligned Deployment in Politically Sensitive Environmentscited by 0
- 2026Detecting Data Contamination in Large Language Modelscited by 0
- 2026VeriScale: Adversarial Test-Suite Scaling for Verifiable Code Generationcited by 0
- 2026On the Memorization Behavior of LLMs in Generative Recommendation: Observations, Implications, and Training Strategiescited by 0
- 2026Implicit Reasoning Steering via Concept Chainingcited by 0
- 2026Memorization Is Not Extraction: Tight Differential-Privacy Bounds and Audit Blind Spotscited by 0
- 2026Is Memorization Context-Sensitive? Prefix-Based Extraction Beyond Isolated Prefixescited by 0
- 2026Is Memorization Context-Sensitive? Prefix-Based Extraction Beyond Isolated Prefixes8 Oct 2026
- 2026Memorization Is Not Extraction: Tight Differential-Privacy Bounds and Audit Blind Spots27 Aug 2026
- 2026Implicit Reasoning Steering via Concept Chaining15 Jul 2026
- 2026On the Memorization Behavior of LLMs in Generative Recommendation: Observations, Implications, and Training Strategies15 Jun 2026
- 2026VeriScale: Adversarial Test-Suite Scaling for Verifiable Code Generation21 May 2026
- 2026Detecting Data Contamination in Large Language Models21 Apr 2026
- 2026Operationalising the Right to be Forgotten in LLMs: A Lightweight Sequential Unlearning Framework for Privacy-Aligned Deployment in Politically Sensitive Environments14 Apr 2026
- 2026GR-SAP: Generative Replay for Safety Alignment Preservation during Fine-Tuning10 Mar 2026
- 2026Reward Modeling for Reinforcement Learning-Based LLM Reasoning: Design, Challenges, and Evaluation10 Feb 2026
- 2026Membership Inference Attacks Against Fine-tuned Diffusion Language Models27 Jan 2026
- 2026A Survey on Evaluating Quality and Trustworthiness in LLM-Generated Data25 Jan 2026
- 2025Randomized Masked Finetuning: An Efficient Way to Mitigate Memorization of PIIs in LLMs2 Dec 2025
17 more
- 2025Comparing Reconstruction Attacks on Pretrained Versus Full Fine-tuned Large Language Model Embeddings on Homo Sapiens Splice Sites Genomic Data9 Nov 2025
- 2025Extracting alignment data in open models21 Oct 2025
- 2025KnowRL: Teaching Language Models to Know What They Know13 Oct 2025
- 2025A Survey of Reinforcement Learning for Large Reasoning Models10 Sep 2025
- 2025Memorization in Large Language Models in Medicine: Prevalence, Characteristics, and Implications10 Sep 2025
- 2025Memorization neq Understanding: Do Large Language Models Have the Ability of Scenario Cognition?5 Sep 2025
- 2025Rote Learning Considered Useful: Generalizing over Memorized Data in LLMs29 Jul 2025
- 2025Rethinking Memorization Measures and their Implications in Large Language Models20 Jul 2025
- 2025The Landscape of Memorization in LLMs: Mechanisms, Measurement, and Mitigation8 Jul 2025
- 2025Mirage of Mastery: Memorization Tricks LLMs into Artificially Inflated Self-Knowledge23 Jun 2025
- 2025Beyond Public Access in LLM Pre-Training Data24 Apr 2025
- 2025We Are All Creators: Generative AI, Collective Knowledge, and the Path Towards Human-AI Synergy10 Apr 2025
- 2025Factored Agents: Decoupling In-Context Learning and Memorization for Robust Tool Use29 Mar 2025
- 2025Trustworthy Machine Learning via Memorization and the Granular Long-Tail: A Survey on Interactions, Tradeoffs, and Beyond10 Mar 2025
- 2025Mitigating Memorization in LLMs using Activation Steering8 Mar 2025
- 2025Watch Out Your Album! On the Inadvertent Privacy Memorization in Multi-Modal Large Language Models3 Mar 2025
- 2025R.R.: Unveiling LLM Training Privacy through Recollection and Ranking18 Feb 2025
- 2025A Survey of Reinforcement Learning for Large Reasoning Modelscited by 175
- 2026Reward Modeling for Reinforcement Learning-Based LLM Reasoning: Design, Challenges, and Evaluationcited by 5
- 2025Rethinking Memorization Measures and their Implications in Large Language Modelscited by 1
- 2026Implicit Reasoning Steering via Concept Chainingcited by 0
- 2026Implicit Reasoning Steering via Concept Chaining15 Jul 2026
- 2026Reward Modeling for Reinforcement Learning-Based LLM Reasoning: Design, Challenges, and Evaluation10 Feb 2026
- 2025A Survey of Reinforcement Learning for Large Reasoning Models10 Sep 2025
- 2025Rethinking Memorization Measures and their Implications in Large Language Models20 Jul 2025
- 2025R.R.: Unveiling LLM Training Privacy through Recollection and Rankingcited by 10
- 2025The Landscape of Memorization in LLMs: Mechanisms, Measurement, and Mitigationcited by 9
- 2025Beyond Public Access in LLM Pre-Training Datacited by 3
- 2026Operationalising the Right to be Forgotten in LLMs: A Lightweight Sequential Unlearning Framework for Privacy-Aligned Deployment in Politically Sensitive Environmentscited by 0
- 2026Operationalising the Right to be Forgotten in LLMs: A Lightweight Sequential Unlearning Framework for Privacy-Aligned Deployment in Politically Sensitive Environments14 Apr 2026
- 2025The Landscape of Memorization in LLMs: Mechanisms, Measurement, and Mitigation8 Jul 2025
- 2025Beyond Public Access in LLM Pre-Training Data24 Apr 2025
- 2025R.R.: Unveiling LLM Training Privacy through Recollection and Ranking18 Feb 2025
- 2025Mitigating Memorization in LLMs using Activation Steeringcited by 7
- 2025Extracting alignment data in open modelscited by 7
- 2025Trustworthy Machine Learning via Memorization and the Granular Long-Tail: A Survey on Interactions, Tradeoffs, and Beyondcited by 6
- 2025Rote Learning Considered Useful: Generalizing over Memorized Data in LLMscited by 5
- 2025Memorization in Large Language Models in Medicine: Prevalence, Characteristics, and Implicationscited by 5
- 2025KnowRL: Teaching Language Models to Know What They Knowcited by 5
- 2025Mirage of Mastery: Memorization Tricks LLMs into Artificially Inflated Self-Knowledgecited by 2
- 2025Memorization neq Understanding: Do Large Language Models Have the Ability of Scenario Cognition?cited by 1
- 2025We Are All Creators: Generative AI, Collective Knowledge, and the Path Towards Human-AI Synergycited by 0
- 2025Comparing Reconstruction Attacks on Pretrained Versus Full Fine-tuned Large Language Model Embeddings on Homo Sapiens Splice Sites Genomic Datacited by 0
- 2025Randomized Masked Finetuning: An Efficient Way to Mitigate Memorization of PIIs in LLMscited by 0
- 2026Detecting Data Contamination in Large Language Modelscited by 0
12 most cited of 16 All 16 (JSON)
- 2026Is Memorization Context-Sensitive? Prefix-Based Extraction Beyond Isolated Prefixes8 Oct 2026
- 2026Memorization Is Not Extraction: Tight Differential-Privacy Bounds and Audit Blind Spots27 Aug 2026
- 2026On the Memorization Behavior of LLMs in Generative Recommendation: Observations, Implications, and Training Strategies15 Jun 2026
- 2026VeriScale: Adversarial Test-Suite Scaling for Verifiable Code Generation21 May 2026
- 2026Detecting Data Contamination in Large Language Models21 Apr 2026
- 2025Randomized Masked Finetuning: An Efficient Way to Mitigate Memorization of PIIs in LLMs2 Dec 2025
- 2025Comparing Reconstruction Attacks on Pretrained Versus Full Fine-tuned Large Language Model Embeddings on Homo Sapiens Splice Sites Genomic Data9 Nov 2025
- 2025Extracting alignment data in open models21 Oct 2025
- 2025KnowRL: Teaching Language Models to Know What They Know13 Oct 2025
- 2025Memorization in Large Language Models in Medicine: Prevalence, Characteristics, and Implications10 Sep 2025
- 2025Memorization neq Understanding: Do Large Language Models Have the Ability of Scenario Cognition?5 Sep 2025
- 2025Rote Learning Considered Useful: Generalizing over Memorized Data in LLMs29 Jul 2025
12 newest of 16 All 16 (JSON)
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