--- title: IonStack part II: GhostLock, a stack-UAF that has... description: GhostLock (CVE-2026-43499) is a Linux kernel stack use-after-free vulnerability present in every major Linux distribution since 2011 (Linux 2.6.39 through... canonical: https://daily.dev/posts/ionstack-part-ii-ghostlock-a-stack-uaf-that-has-existed-in-all-linux-distributions-for-15-years-wznoxduhk twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: IonStack part II: GhostLock, a stack-UAF that has existed in ALL Linux distributions for 15 years | daily.dev og:description: GhostLock (CVE-2026-43499) is a Linux kernel stack use-after-free vulnerability present in every major Linux distribution since 2011 (Linux 2.6.39 through... og:url: https://daily.dev/posts/ionstack-part-ii-ghostlock-a-stack-uaf-that-has-existed-in-all-linux-distributions-for-15-years-wznoxduhk og:image: https://api.daily.dev/og/posts/wZNoxDUhk.png og:image:alt: IonStack part II: GhostLock, a stack-UAF that has existed in ALL Linux distributions for 15 years 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. # IonStack part II: GhostLock, a stack-UAF that has existed in ALL Linux distributions for 15 years **[Hacker News](https://daily.dev/sources/hn)** · 16 min read · 2 upvotes · 0 comments ## Summary GhostLock (CVE-2026-43499) is a Linux kernel stack use-after-free vulnerability present in every major Linux distribution since 2011 (Linux 2.6.39 through 7.1). The bug lives in rtmutex's remove_waiter() function, which incorrectly clears pi_blocked_on on the wrong task during a FUTEX_CMP_REQUEUE_PI deadlock rollback, leaving a dangling pointer into freed kernel stack memory. No special privileges or kernel configuration are required beyond CONFIG_FUTEX_PI=y. The writeup details the full exploit chain: leaking KASLR via prefetch timing, reclaiming the freed stack frame using PR_SET_MM_MAP with a forged rt_mutex_waiter, performing a constrained pointer write to overwrite inet6_protos[IPPROTO_UDP] with a CPU entry area address, triggering control flow hijack via a loopback IPv6 UDP packet, and using a short ROP chain with the DirtyMode technique to make core_pattern world-writable for unprivileged LPE. The exploit achieves 97% stability and earned $92,337 in Google's kernelCTF. Full PoC code is open-sourced. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: --- Tags: [#security](https://daily.dev/tags/security), [#linux](https://daily.dev/tags/linux) [View this post on daily.dev](https://daily.dev/posts/ionstack-part-ii-ghostlock-a-stack-uaf-that-has-existed-in-all-linux-distributions-for-15-years-wznoxduhk) ```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":"IonStack part II: GhostLock, a stack-UAF that has existed in ALL Linux distributions for 15 years","url":"https://daily.dev/posts/ionstack-part-ii-ghostlock-a-stack-uaf-that-has-existed-in-all-linux-distributions-for-15-years-wznoxduhk","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/ionstack-part-ii-ghostlock-a-stack-uaf-that-has-existed-in-all-linux-distributions-for-15-years-wznoxduhk"},"datePublished":"2026-07-11T03:27:57.511Z","dateModified":"2026-07-11T03:28:24.650Z","description":"GhostLock (CVE-2026-43499) is a Linux kernel stack use-after-free vulnerability present in every major Linux distribution since 2011 (Linux 2.6.39 through...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/2a95587ff18e1dd37637f375356c6a50?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/2a95587ff18e1dd37637f375356c6a50?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Hacker News","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":"Hacker News","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/hn","url":"https://daily.dev/sources/hn"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/ionstack-part-ii-ghostlock-a-stack-uaf-that-has-existed-in-all-linux-distributions-for-15-years-wznoxduhk","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":2},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"security,linux","timeRequired":"PT16M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Hacker News","item":"https://daily.dev/sources/hn"},{"@type":"ListItem","position":3,"name":"IonStack part II: GhostLock, a stack-UAF that has existed in ALL Linux distributions for 15 years"}]} ```