Anthropic says it found a heap of Firefox security flaws using new Claude tools, says 'AI is making it possible to detect severe security vulnerabilities at highly accelerated speeds'

Date:
Mon, 09 Mar 2026 14:05:00 +0000

Description:
Claude finds 14 high-severity Firefox bugs in just a few weeks, rivaling what Mozilla could do in months.

FULL STORY ======================================================================Copy link Facebook X Whatsapp Reddit Pinterest Flipboard Threads Email Share this article 0 Join the conversation Follow us Add us as a preferred source on Google Newsletter Tech Radar Get the TechRadar Newsletter Sign up for
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now subscribed Your newsletter sign-up was successful An account already exists for this email address, please log in. Subscribe to our newsletter Anthropic Claude Opus 4.6 uncovers 22 Firefox security flaws Mozilla
confirmed 14 high-severity vulnerabilities patched in Firefox 148 AI model demonstrated accelerated, human-like vulnerability detection Anthropic says
it found almost two dozen vulnerabilities in the latest version of Mozillas Firefox browser , including a few that could have caused serious damage.

In a new blog post Anthropic said it teamed up with Mozillas researchers and, over the course of a couple weeks, scanned almost 6,000 C++ files using
Claude Opus 4.6. Opus 4.6 is the latest version of Anthropics most powerful large language model (LLM), which was released in early February 2026, and
has been advertised as a must-have tool in every cyber defenders arsenal, claiming it is notably better at finding high-severity vulnerabilities. Article continues below You may like Anthropic says its new Opus 4.6 platform found over 500 previously unknown high-severity security flaws in open-source libraries during testing Security experts flag multiple issues in Claude
Code, warning, 'As AI integration deepens, security controls must evolve to match the new trust boundaries' One job where AI stepping up isn't such a problem - AI-assisted cybersecurity team discovers mass of OpenSSL vulnerabilities, praised for 'high quality of the reports and their constructive collaboration' Major success After analyzing popular open source repositories and finding more than 500 flaws, Anthropic set its sights to Firefox, mostly because it is both complex and one of the most well-tested
and secure open-source projects in the world. In other words, it really
wanted to prove a point by finding a product thats generally considered
large, and safe.

The team ran the experiment for two weeks, and in that timeframe, Opus 4.6 managed to find 22 vulnerabilities. Mozilla labeled 14 of them as high severity. In total, Anthropic submitted a total of 112 unique reports, most
of which were addressed in Firefox 148. The remainder will be fixed in upcoming releases, it was said.

Anthropic is framing this as a major success, saying Opus 4.6 uncovered in
two weeks roughly a fifth as many high-severity vulnerabilities as Mozilla fixed during all of 2025.

AI is making it possible to detect severe security vulnerabilities at highly accelerated speeds, they said. Earlier, Anthropic said Opus 4.6 stood out
with the way it found vulnerabilities out of the box without task-specific tooling, custom scaffolding, or specialized prompting. Are you a pro? Subscribe to our newsletter Sign up to the TechRadar Pro newsletter to get
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It also added unlike fuzzing, which is a standard vulnerability hunting technique, Opus works by reasoning about the code the way a human researcher would, meaning it was looking at past fixes to find similar bugs that werent addressed, spotting patterns that tend to cause problems, and was understanding logic well enough to know exactly what input would break it.
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