REBEL: Hidden Knowledge Recovery via Evolutionary-Based Evaluation Loop

Fuente: arXiv
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Autores principales: Rybak, Patryk, Batorski, Paweł, Swoboda, Paul, Spurek, Przemysław
Formato: Preprint
Publicado: 2026
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author Rybak, Patryk
Batorski, Paweł
Swoboda, Paul
Spurek, Przemysław
author_facet Rybak, Patryk
Batorski, Paweł
Swoboda, Paul
Spurek, Przemysław
contents Machine unlearning for LLMs aims to remove sensitive or copyrighted data from trained models. However, the true efficacy of current unlearning methods remains uncertain. Standard evaluation metrics rely on benign queries that often mistake superficial information suppression for genuine knowledge removal. Such metrics fail to detect residual knowledge that more sophisticated prompting strategies could still extract. We introduce REBEL, an evolutionary approach for adversarial prompt generation designed to probe whether unlearned data can still be recovered. Our experiments demonstrate that REBEL successfully elicits ``forgotten'' knowledge from models that seemed to be forgotten in standard unlearning benchmarks, revealing that current unlearning methods may provide only a superficial layer of protection. We validate our framework on subsets of the TOFU and WMDP benchmarks, evaluating performance across a diverse suite of unlearning algorithms. Our experiments show that REBEL consistently outperforms static baselines, recovering ``forgotten'' knowledge with Attack Success Rates (ASRs) reaching up to 60% on TOFU and 93% on WMDP. We will make all code publicly available upon acceptance. Code is available at https://github.com/patryk-rybak/REBEL/
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id arxiv_https___arxiv_org_abs_2602_06248
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle REBEL: Hidden Knowledge Recovery via Evolutionary-Based Evaluation Loop
Rybak, Patryk
Batorski, Paweł
Swoboda, Paul
Spurek, Przemysław
Machine Learning
Artificial Intelligence
Machine unlearning for LLMs aims to remove sensitive or copyrighted data from trained models. However, the true efficacy of current unlearning methods remains uncertain. Standard evaluation metrics rely on benign queries that often mistake superficial information suppression for genuine knowledge removal. Such metrics fail to detect residual knowledge that more sophisticated prompting strategies could still extract. We introduce REBEL, an evolutionary approach for adversarial prompt generation designed to probe whether unlearned data can still be recovered. Our experiments demonstrate that REBEL successfully elicits ``forgotten'' knowledge from models that seemed to be forgotten in standard unlearning benchmarks, revealing that current unlearning methods may provide only a superficial layer of protection. We validate our framework on subsets of the TOFU and WMDP benchmarks, evaluating performance across a diverse suite of unlearning algorithms. Our experiments show that REBEL consistently outperforms static baselines, recovering ``forgotten'' knowledge with Attack Success Rates (ASRs) reaching up to 60% on TOFU and 93% on WMDP. We will make all code publicly available upon acceptance. Code is available at https://github.com/patryk-rybak/REBEL/
title REBEL: Hidden Knowledge Recovery via Evolutionary-Based Evaluation Loop
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2602.06248