---
title: "Anthropic's Claude Mythos model found new cryptographic weaknesses"
url: https://www.parallelquant.com/posts/anthropic-s-claude-mythos-model-found-new-cryptographic-weaknesses-1c7830
source_name: "The Decoder"
source_url: https://the-decoder.com/anthropic-says-its-mythos-model-found-vulnerabilities-in-cryptographic-algorithms-that-secure-the-internet/
published: 2026-07-28T19:12:27.000Z
topics: ["research", "security"]
publisher: "Parallel Quant"
---

# Anthropic's Claude Mythos model found new cryptographic weaknesses

*2026-07-28 · Source: [The Decoder](https://the-decoder.com/anthropic-says-its-mythos-model-found-vulnerabilities-in-cryptographic-algorithms-that-secure-the-internet/)*

Anthropic says its Claude Mythos Preview model discovered weaknesses in cryptographic algorithms that secure the internet, including an improved attack on HAWK, a post-quantum signature scheme human experts had reviewed for over two years. The model found the weakness in about 60 hours at an estimated API cost of $100,000. Anthropic says the findings don't affect systems currently in use.

**Why it matters:** This shows a frontier model producing genuinely novel cryptanalysis that professional cryptographers missed for years, not just summarizing known security research — a real capability jump with dual-use implications, since the skill that finds flaws to fix them could also find flaws to exploit. Coming the same week as the OpenAI/Hugging Face agent intrusion story, it adds weight to the safety statements above: offensive and security-relevant AI capabilities appear to be advancing faster than institutions have adjusted for.

**Topics:** research, security

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Read the original: https://the-decoder.com/anthropic-says-its-mythos-model-found-vulnerabilities-in-cryptographic-algorithms-that-secure-the-internet/
Canonical: https://www.parallelquant.com/posts/anthropic-s-claude-mythos-model-found-new-cryptographic-weaknesses-1c7830
Published by Parallel Quant — https://www.parallelquant.com