--- title: An AI agent built a working exploit for this macOS flaw... description: A macOS Screen Sharing vulnerability (CVE-2026-65400) allowing pre-authentication root access is under active exploitation, with attackers deploying Monero... canonical: https://daily.dev/posts/an-ai-agent-built-a-working-exploit-for-this-macos-flaw-in-four-hours-nsxa0laum twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: An AI agent built a working exploit for this macOS flaw in four hours | daily.dev og:description: A macOS Screen Sharing vulnerability (CVE-2026-65400) allowing pre-authentication root access is under active exploitation, with attackers deploying Monero... og:url: https://daily.dev/posts/an-ai-agent-built-a-working-exploit-for-this-macos-flaw-in-four-hours-nsxa0laum og:image: https://api.daily.dev/og/posts/nSxA0laUM.png og:image:alt: An AI agent built a working exploit for this macOS flaw in four hours og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # An AI agent built a working exploit for this macOS flaw in four hours **[The Next Web](https://daily.dev/sources/tnw)** · 5 min read · 0 upvotes · 0 comments ## Summary A macOS Screen Sharing vulnerability (CVE-2026-65400) allowing pre-authentication root access is under active exploitation, with attackers deploying Monero cryptominers on compromised Macs. Security firm Calif used an AI agent to build a working exploit in just four hours after reverse-engineering Apple's out-of-band patch, prompting the firm to withhold technical details until more systems are patched. Apple fixed the issue in macOS Tahoe 26.6.1, Sequoia 15.7.9, and Sonoma 14.8.9, but roughly 40,000 Macs with Screen Sharing exposed to the internet remain at risk. Vulnerability scoring is inconsistent across agencies: the Dutch NCSC rates it 7.1, CISA rates it 9.8, and NIST has not yet assessed it. Users are advised to patch immediately or disable Screen Sharing and block port 5900. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What is CVE-2026-65400 and is it being actively exploited? CVE-2026-65400 is a pre-authentication vulnerability in macOS Screen Sharing that lets an attacker on the network authenticate to the remote desktop service without valid credentials, gaining root access. The Dutch National Cyber Security Centre confirmed active abuse, finding that every compromised system had port 5900 open to the internet, with root access followed by installation of a Monero crypto miner in all confirmed cases. _Track fast-moving vulnerabilities like this one on daily.dev before they hit your fleet._ ### Which macOS versions fix the Screen Sharing root vulnerability? Apple shipped fixes in macOS Tahoe 26.6.1, Sequoia 15.7.9, and Sonoma 14.8.9, published in an advisory on August 6. The bug was credited to Alfredo Pesoli of security firm Bynario. If patching isn't immediately possible, turning off Screen Sharing in System Settings under General > Sharing, or blocking port 5900 at the firewall, reduces exposure as a fallback measure. _Developers managing Mac fleets can follow patch guidance like this via daily.dev._ ### How long did it take an AI agent to build a working exploit for the macOS Screen Sharing flaw? An AI agent used by security firm Calif produced working exploits for two separate pre-authentication remote root bugs in macOS within four hours, after the firm reverse-engineered Apple's out-of-band update. Calif withheld technical details of CVE-2026-65400 specifically because the exploit was too easy to produce, delaying disclosure until more Macs receive the patch. _Stay ahead of the AI-accelerated exploit development cycle by following security research on daily.dev._ ## Similar posts on daily.dev - [First public macOS kernel memory corruption exploit on Apple M5](https://daily.dev/posts/first-public-macos-kernel-memory-corruption-exploit-on-apple-m5-mutpamz3w) · Hacker News · 4 upvotes · 0 comments - [Apple patches CoreGraphics zero-day flaw exploited in attacks](https://daily.dev/posts/apple-patches-coregraphics-zero-day-flaw-exploited-in-attacks-0ov4mhz7v) · BleepingComputer · 2 upvotes · 0 comments --- Tags: [#security](https://daily.dev/tags/security), [#apple](https://daily.dev/tags/apple), [#ai-agents](https://daily.dev/tags/ai-agents), [#mac](https://daily.dev/tags/mac) [View this post on daily.dev](https://daily.dev/posts/an-ai-agent-built-a-working-exploit-for-this-macos-flaw-in-four-hours-nsxa0laum) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"An AI agent built a working exploit for this macOS flaw in four hours","url":"https://daily.dev/posts/an-ai-agent-built-a-working-exploit-for-this-macos-flaw-in-four-hours-nsxa0laum","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/an-ai-agent-built-a-working-exploit-for-this-macos-flaw-in-four-hours-nsxa0laum"},"datePublished":"2026-08-17T22:52:52.446Z","dateModified":"2026-08-21T15:51:18.135Z","description":"A macOS Screen Sharing vulnerability (CVE-2026-65400) allowing pre-authentication root access is under active exploitation, with attackers deploying Monero...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/a849914749501277ee464b9317e2f962?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/a849914749501277ee464b9317e2f962?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"The Next Web","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"The Next Web","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/tnw","url":"https://daily.dev/sources/tnw"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/an-ai-agent-built-a-working-exploit-for-this-macos-flaw-in-four-hours-nsxa0laum","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"security,apple,ai-agents,mac","timeRequired":"PT5M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"The Next Web","item":"https://daily.dev/sources/tnw"},{"@type":"ListItem","position":3,"name":"An AI agent built a working exploit for this macOS flaw in four hours"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/an-ai-agent-built-a-working-exploit-for-this-macos-flaw-in-four-hours-nsxa0laum#faq","mainEntity":[{"@type":"Question","name":"What is CVE-2026-65400 and is it being actively exploited?","acceptedAnswer":{"@type":"Answer","text":"CVE-2026-65400 is a pre-authentication vulnerability in macOS Screen Sharing that lets an attacker on the network authenticate to the remote desktop service without valid credentials, gaining root access. The Dutch National Cyber Security Centre confirmed active abuse, finding that every compromised system had port 5900 open to the internet, with root access followed by installation of a Monero crypto miner in all confirmed cases. Track fast-moving vulnerabilities like this one on daily.dev before they hit your fleet."}},{"@type":"Question","name":"Which macOS versions fix the Screen Sharing root vulnerability?","acceptedAnswer":{"@type":"Answer","text":"Apple shipped fixes in macOS Tahoe 26.6.1, Sequoia 15.7.9, and Sonoma 14.8.9, published in an advisory on August 6. The bug was credited to Alfredo Pesoli of security firm Bynario. If patching isn't immediately possible, turning off Screen Sharing in System Settings under General > Sharing, or blocking port 5900 at the firewall, reduces exposure as a fallback measure. Developers managing Mac fleets can follow patch guidance like this via daily.dev."}},{"@type":"Question","name":"How long did it take an AI agent to build a working exploit for the macOS Screen Sharing flaw?","acceptedAnswer":{"@type":"Answer","text":"An AI agent used by security firm Calif produced working exploits for two separate pre-authentication remote root bugs in macOS within four hours, after the firm reverse-engineered Apple's out-of-band update. Calif withheld technical details of CVE-2026-65400 specifically because the exploit was too easy to produce, delaying disclosure until more Macs receive the patch. Stay ahead of the AI-accelerated exploit development cycle by following security research on daily.dev."}}]} ```