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LLM Reasoning Traces Leaked Via API Vulnerability

A new paper reveals a vulnerability in proprietary LLM APIs from Anthropic, OpenAI, and Google, allowing encrypted reasoning traces to be extracted and replayed. Researchers demonstrated that these encrypted "thought blocks" are interchangeable across models and sessions within the same provider's ecosystem. By injecting an encrypted trace into a weaker model, attackers can force it to reveal the stronger model's hidden reasoning, bypassing anti-distillation measures. This technique can also expose sensitive data like API keys and personal information that were inadvertently included in these hidden traces, and potentially enable invisible prompt injections. AI

IMPACT Exposes sensitive data and intellectual property, potentially impacting enterprise adoption and security practices for LLM APIs.

RANK_REASON Paper detailing a vulnerability in LLM API reasoning trace encryption.

Read on Hugging Face Daily Papers →

AI-generated summary · Google Gemini · from 8 sources. How we write summaries →

LLM Reasoning Traces Leaked Via API Vulnerability

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Paper detailing a vulnerability in LLM API reasoning trace encryption.
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COVERAGE [8]

  1. Latent Space (swyx) TIER_1 English(EN) ·

    [AINews] How to steal a Reasoning Trace

    Speculative Decoding by any other name would distil as sweet

  2. Simon Willison TIER_1 English(EN) ·

    Stealing Reasoning Traces from Proprietary LLM APIs

    <p><strong><a href="https://stolen-thoughts.com/">Stealing Reasoning Traces from Proprietary LLM APIs</a></strong></p> A vanity domain name (<code>stolen-thoughts.com</code>) for <a href="https://www.alphaxiv.org/abs/2608.09867">a neat paper</a>:</p> <blockquote> <p>Anthropic, Op…

  3. arXiv cs.AI TIER_1 English(EN) · Alexander Panfilov, David Schmotz, Ilia Shumailov, Luca Beurer-Kellner, Joachim Schaeffer, Ameya Prabhu, Jonas Geiping, Maksym Andriushchenko ·

    Stealing Reasoning Traces from Proprietary LLM APIs

    arXiv:2608.09867v1 Announce Type: cross Abstract: Leading large language model providers now conceal their models' step-by-step reasoning, or chain-of-thought, to protect intellectual property and limit information leakage. Rather than storing these traces server-side, providers …

  4. Hugging Face Daily Papers TIER_1 English(EN) ·

    Stealing Reasoning Traces from Proprietary LLM APIs

    Encrypted reasoning traces shared across sessions and models can be intercepted and injected into weaker models to extract proprietary reasoning, private data, hidden hazards, and hidden prompts.

  5. Mastodon — sigmoid.social TIER_1 English(EN) · [email protected] ·

    🤖 Stealing Reasoning Traces from Proprietary LLM APIs Proprietary reasoning can be recovered from its encrypted traces. Anthropic, OpenAI, and Google return enc

    🤖 Stealing Reasoning Traces from Proprietary LLM APIs Proprietary reasoning can be recovered from its encrypted traces. Anthropic, OpenAI, and Google return encrypted chain-of-thought blocks to clients that can be replayed across sessions, users, and ... 📰 Source: Artificial Inte…

  6. dev.to — LLM tag TIER_1 English(EN) · jamilxt ·

    Stealing Reasoning Traces from LLM APIs: How It Works and What to Audit

    <p>A paper from researchers at ELLIS Institute Tübingen, the Max Planck Institute for Intelligent Systems, and Snyk shows that the encrypted reasoning blocks Anthropic, OpenAI, and Google return to API clients are not the protection they look like. The authors replayed a reasonin…

  7. Mastodon — mastodon.social TIER_1 English(EN) · [email protected] ·

    Stealing Reasoning Traces from Proprietary LLM APIs Article URL: https:// stolen-thoughts.com/ Comments URL: https:// news.ycombinator.com/item?id=4 9257876 Poi

    Stealing Reasoning Traces from Proprietary LLM APIs Article URL: https:// stolen-thoughts.com/ Comments URL: https:// news.ycombinator.com/item?id=4 9257876 Points: 13 # Comments: 1 https:// stolen-thoughts.com/ # Tech # Technology # TechNews # AI # Gadgets # Software # Cybersecu…

  8. Mastodon — mastodon.social TIER_1 English(EN) · [email protected] ·

    Stealing Reasoning Traces from Proprietary LLM APIs https://simonwillison.net/2026/Aug/11/stealing-reasoning-traces/#atom-everything # AI # LLM # Research

    Stealing Reasoning Traces from Proprietary LLM APIs https://simonwillison.net/2026/Aug/11/stealing-reasoning-traces/#atom-everything # AI # LLM # Research