{"id":2772,"date":"2026-04-29T11:05:04","date_gmt":"2026-04-29T11:05:04","guid":{"rendered":"https:\/\/blog.ibvl.in\/index.php\/2026\/04\/29\/claude-mythos-has-found-271-zero-days-in-firefox\/"},"modified":"2026-04-29T11:05:04","modified_gmt":"2026-04-29T11:05:04","slug":"claude-mythos-has-found-271-zero-days-in-firefox","status":"publish","type":"post","link":"https:\/\/blog.ibvl.in\/index.php\/2026\/04\/29\/claude-mythos-has-found-271-zero-days-in-firefox\/","title":{"rendered":"Claude Mythos Has Found 271 Zero-Days in Firefox"},"content":{"rendered":"
\n

That\u2019s a lot<\/a>. No, it\u2019s an extraordinary number:<\/p>\n

\n

Since February, the Firefox team has been working around the clock using frontier AI models to find and fix latent security vulnerabilities in the browser. We wrote previously about our collaboration with Anthropic to scan Firefox with Opus 4.6, which led to fixes for 22 security-sensitive bugs in Firefox 148.<\/p>\n

As part of our continued collaboration with Anthropic, we had the opportunity to apply an early version of Claude Mythos Preview to Firefox. This week\u2019s release of Firefox 150 includes fixes for 271 vulnerabilities identified during this initial evaluation.<\/p>\n

As these capabilities reach the hands of more defenders, many other teams are now experiencing the same vertigo we did when the findings first came into focus. For a hardened target, just one such bug would have been red-alert in 2025, and so many at once makes you stop to wonder whether it\u2019s even possible to keep up.<\/p>\n

Our experience is a hopeful one for teams who shake off the vertigo and get to work. You may need to reprioritize everything else to bring relentless and single-minded focus to the task, but there is light at the end of the tunnel. We are extremely proud of how our team rose to meet this challenge, and others will too. Our work isn\u2019t finished, but we\u2019ve turned the corner and can glimpse a future much better than just keeping up. Defenders finally have a chance to win, decisively.<\/strong><\/p>\n<\/blockquote>\n

They\u2019re right. Assuming the defenders can patch, and push those patches out to users quickly, this technology favors the defenders.<\/p>\n

News article<\/a>.<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

That\u2019s a lot. No, it\u2019s an extraordinary number: Since February, the Firefox team has been working around the clock using frontier AI models to find and fix latent security vulnerabilities in the browser. We wrote previously about our collaboration with Anthropic to scan Firefox with Opus 4.6, which led to fixes for 22 security-sensitive bugs […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-container-style":"default","site-container-layout":"default","site-sidebar-layout":"default","disable-article-header":"default","disable-site-header":"default","disable-site-footer":"default","disable-content-area-spacing":"default","footnotes":""},"categories":[4,90,501,53,602],"tags":[91],"class_list":["post-2772","post","type-post","status-publish","format-standard","hentry","category-ai","category-cybersecurity","category-firefox","category-uncategorized","category-zero-day","tag-cybersecurity"],"yoast_head":"\nClaude Mythos Has Found 271 Zero-Days in Firefox - Imperative Business Ventures Limited<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/blog.ibvl.in\/index.php\/2026\/04\/29\/claude-mythos-has-found-271-zero-days-in-firefox\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Claude Mythos Has Found 271 Zero-Days in Firefox - Imperative Business Ventures Limited\" \/>\n<meta property=\"og:description\" content=\"That\u2019s a lot. 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