Claude Mythos Audited Symfony and Found 19 Vulnerabilities
Claude Mythos Preview, an AI model by Anthropic, conducted a security audit of Symfony and Twig, identifying 19 vulnerabilities. All reported vulnerabilities were confirmed as real by the Symfony Core Team, leading to immediate fixes in the latest security releases. This initiative highlights the evolving landscape of code security auditing through advanced AI technologies.
- ▪Claude Mythos Preview is a new AI language model by Anthropic, particularly strong in computer security tasks.
- ▪The model identified 19 real vulnerabilities in Symfony and Twig, all of which were addressed in recent security updates.
- ▪This audit is part of a broader trend where AI tools are revolutionizing code security assessments.
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Source · retrieval · rights · ranking — open for full record
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Attribution is not the same as permission. This drawer separates discovery metadata, excerpts, WeSearch-generated summaries, reuse status, and whether the publisher receives the visit. Nothing here claims a legal grant the publisher has not made.
Record
| Original publisher | Symfony |
| Canonical URL | https://symfony.com/blog/claude-mythos-audited-symfony-and-found-19-vulnerabilities |
| Publication time | Thu, 21 May 2026 07:45:56 +0000 |
| Retrieval time | 2026-05-21T08:05:03.760Z |
| Last seen | 2026-05-21T08:05:03.760Z |
| Headline source | Publisher (no WeSearch rewrite) |
| Excerpt source | publisher body |
| Excerpt method | First ~120 words (~800 chars) of extracted publisher body, fair-use limited. |
| Summary | WeSearch · cerebras-chat (WeSearch summarizer) |
| Summary source text | contentText |
| Citation coverage | Summary is a WeSearch-generated derivative; primary citation is the original publisher URL. |
| Cluster | _CcSEiKPk8T3 · 2 stories |
| Cluster logic | Grouped by semantic title/content similarity across sources within a rolling window. Same-publisher template collisions are excluded from coverage comparison. |
| Ranking reason | Story pages are not engagement-ranked. Hub feeds use recency, with optional source-diversified chronological ordering (cap consecutive stories per source). No personalized ranking. |
| Publisher visit | Yes — open original |
| Substitutes article? | No — link-out required for full text |
Rights status (four layers)
WeSearch handling by dimension
| Indexing | May the item be indexed (stored, ranked, made findable)? | Allowed |
| Snippet | May a short excerpt of the publisher's text be shown? | Allowed |
| AI summary | May WeSearch generate its own short summary of the article? | Limited |
| Retrieval / RAG | May the content be exposed for third-party retrieval-augmented generation? | Not asserted |
| Model training | May the content be used to train AI models? | Not asserted |
| Commercial reuse | May the content be reused commercially? | Not permitted |
Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.
Opening excerpt (first ~120 words) tap to expand
Claude Mythos Audited Symfony and Found 19 Vulnerabilities May 21, 2026 • Published by Javier Eguiluz Claude Mythos Preview is a new general-purpose AI language model by Anthropic. This model performs strongly across the board, but it is especially strong at computer security tasks. This model is not publicly available yet, but Anthropic is making it available to selected tech projects via their Project Glasswing. Through this initiative, Claude Mythos has found thousands of security vulnerabilities, including some in every major operating system and web browser. Symfony recently teamed up with The PHP Foundation and Anthropic to build the official MCP SDK for PHP applications.
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Excerpt limited to ~120 words for fair-use compliance. The full article is at Symfony.
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