Seed Hijacking of LLM Sampling and Quantum Random Number Defense
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Abstract (arXiv)
Large language models (LLMs) rely on deterministic pseudorandom number generators (PRNGs) for autoregressive sampling, creating a critical supply-chain attack surface overlooked by existing defenses. We present SeedHijack, a backdoor attack that manipulates PRNG outputs to force attacker-specified token selection without altering model logits. In a 540-trial benchmark on GPT-2 (124M), the attack achieves 99.6% exact token injection across 9 sampling configurations; it reaches 100% success on four aligned models (1.5B-7B, RLHF/SFT/reasoning distillation) and bypasses all alignment methods tested in this work. We further propose a defense based on a hardware quantum random number generator (QRNG), which neutralizes the attack in our evaluated threat model with negligible median overhead (+0.6% latency, +7.7 MB memory). Our work identifies a critical sampling-layer vulnerability and provides a practical, deployable QRNG-based defense.
Key facts. Cited by 1 paper in the map (data through 7 Oct 2026). Builds on 16 of its 28 references that are in the map. First posted on arXiv 8 May 2026.
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16 of 28 references.
References · 16
- 2022Training language models to follow instructions with human feedbackcited by 15,712
- 2023Direct Preference Optimization: Your Language Model is Secretly a Reward Modelcited by 7,916
- 2014Explaining and Harnessing Adversarial Examplescited by 7,287
- 2017Towards Deep Learning Models Resistant to Adversarial Attackscited by 6,326
- 2019The Curious Case of Neural Text Degenerationcited by 2,881
- 2019Certified Adversarial Robustness via Randomized Smoothingcited by 1,324
- 2023BeaverTails: Towards Improved Safety Alignment of LLM via a Human-Preference Datasetcited by 828
- 2017Provable defenses against adversarial examples via the convex outer adversarial polytopecited by 564
- 2024JailbreakBench: An Open Robustness Benchmark for Jailbreaking Large Language Modelscited by 494
- 2018Certified Defenses against Adversarial Examplescited by 305
- 2017Certified Defenses for Data Poisoning Attackscited by 288
- 2024Bag of Tricks: Benchmarking of Jailbreak Attacks on LLMscited by 47
4 more
- 2023Conformal Nucleus Samplingcited by 32
- 2025FC-Attack: Jailbreaking Multimodal Large Language Models via Auto-Generated Flowchartscited by 15
- 2024Stealthy Jailbreak Attacks on Large Language Models via Benign Data Mirroringcited by 10
- 2023Machine Learning needs Better Randomness Standards: Randomised Smoothing and PRNG-based attackscited by 6
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Citing papers per year: 2026: 1.
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- 2025Beyond the Benchmark: Innovative Defenses Against Prompt Injection Attacks
- 2025On Jailbreaking Quantized Language Models Through Fault Injection Attacks
- 2026The Joint Effect of Quantization and Sampling Temperature on LLM Safety Alignment: A Factorial Analysis
- 2025Token-Efficient Prompt Injection Attack: Provoking Cessation in LLM Reasoning via Adaptive Token Compression
- 2026AGENTQ: Quantization-Conditioned Backdoor Attacks on LLM Agents
- 2026Controlled Decoding Attacks on Black-Box LLMs