{"id":"CVE-2026-89750","title":"tracing/user_events: Clear copied tracing state before fork duplication","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing/user_events: Clear copied tracing state before fork duplication\n\ndup_task_struct() copies user_event_mm from the parent into the child,\nwithout grabbing a refer…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","cwe":["CWE-825"],"vendor":"Linux","product":"Linux","affected":["Linux >= 7235759084a4f8524a46bd2638885ff3b34ce279 < 33ce55b368b64d65941867add00e7f288cbb8234","Linux >= 7235759084a4f8524a46bd2638885ff3b34ce279 < 63b39e49a4c9d68e010e96b26fc7374f0864f2b1","Linux >= 7235759084a4f8524a46bd2638885ff3b34ce279 < 25a0758cf6bdbfddac2be71124c9bd0692f4b0b1","Linux >= 7235759084a4f8524a46bd2638885ff3b34ce279 < b799f67119aff179719a0b1e12441ebbdaaf62f9","Linux >= 7235759084a4f8524a46bd2638885ff3b34ce279 < 390f6bd8583d177029d9df4bea6667509e55a765","Linux 6.4"],"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:52:04.079Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89750","references":[{"url":"https://git.kernel.org/stable/c/33ce55b368b64d65941867add00e7f288cbb8234"},{"url":"https://git.kernel.org/stable/c/63b39e49a4c9d68e010e96b26fc7374f0864f2b1"},{"url":"https://git.kernel.org/stable/c/25a0758cf6bdbfddac2be71124c9bd0692f4b0b1"},{"url":"https://git.kernel.org/stable/c/b799f67119aff179719a0b1e12441ebbdaaf62f9"},{"url":"https://git.kernel.org/stable/c/390f6bd8583d177029d9df4bea6667509e55a765"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89750.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89750"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532248"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89750"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89750"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89750.mbox"}],"tags":["cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00163,"epssPercentile":0.05464,"scores":{"cna":7.8,"vendor":5.5},"ingestedAt":"2026-09-14T15:23:07.448Z","slug":"CVE-2026-89750","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\ntracing/user_events: Clear copied tracing state before fork duplication\n\ndup_task_struct() copies user_event_mm from the parent into the child,\nwithout grabbing a reference to it. user_event_mm_dup() should\nreplace it, but it leaves that copied pointer unmodified if\nuser_event_mm_alloc() fails.\n\nWhen the child exits, user_event_mm_remove() decrements a reference\nthe child never owned, which ultimately frees user_event_mm, while\nthe parent still as a stale pointer to it. This creates a UAF, which\nKASAN reports as:\n\n    BUG: KASAN: slab-use-after-free in\n    current_user_event_mm+0x51/0x1d0 Write of size 4 at addr\n    ffff888005010d30 by task init/44\n\n    Call Trace:\n     <TASK>\n     kasan_report+0xce/0x100\n     kasan_check_range+0x10f/0x1e0\n     current_user_event_mm+0x51/0x1d0\n     user_events_ioctl+0x82e/0x15c0\n     __x64_sys_ioctl+0x139/0x1c0\n     do_syscall_64+0xce/0x450\n     entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\n    Allocated by task 44:\n     __kasan_kmalloc+0x8f/0xa0\n     __kmalloc_cache_noprof+0x180/0x3a0\n     user_event_mm_alloc+0x3c/0x1f0\n     current_user_event_mm+0x88/0x1d0\n\n    Freed by task 42:\n     __kasan_slab_free+0x43/0x70\n     kfree+0x13a/0x390\n     process_one_work+0x696/0xf90\n     worker_thread+0x420/0xba0\n\nThe fix simply clears the copied pointer before any possible failure.\nIn case of failure, the child then has nothing to free.\n\n## Affected\n\n- `Linux >= 7235759084a4f8524a46bd2638885ff3b34ce279 < 33ce55b368b64d65941867add00e7f288cbb8234`\n- `Linux >= 7235759084a4f8524a46bd2638885ff3b34ce279 < 63b39e49a4c9d68e010e96b26fc7374f0864f2b1`\n- `Linux >= 7235759084a4f8524a46bd2638885ff3b34ce279 < 25a0758cf6bdbfddac2be71124c9bd0692f4b0b1`\n- `Linux >= 7235759084a4f8524a46bd2638885ff3b34ce279 < b799f67119aff179719a0b1e12441ebbdaaf62f9`\n- `Linux >= 7235759084a4f8524a46bd2638885ff3b34ce279 < 390f6bd8583d177029d9df4bea6667509e55a765`\n- `Linux 6.4`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89750.json)","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":224576,"id":"CVE-2026-89750","ts":1792401417466,"field":"cvss","old":"5.5","new":"7.8"},{"seq":224575,"id":"CVE-2026-89750","ts":1792401417466,"field":"severity","old":"medium","new":"high"},{"seq":208946,"id":"CVE-2026-89750","ts":1790062297769,"field":"cvss","old":"7.8","new":"5.5"},{"seq":208945,"id":"CVE-2026-89750","ts":1790062297769,"field":"severity","old":"high","new":"medium"},{"seq":197670,"id":"CVE-2026-89750","ts":1789384318328,"field":"cvss","old":"4.7","new":"7.8"},{"seq":197669,"id":"CVE-2026-89750","ts":1789384318328,"field":"severity","old":"medium","new":"high"},{"seq":183657,"id":"CVE-2026-89750","ts":1789356676806,"field":"cvss","old":"7.8","new":"4.7"},{"seq":183656,"id":"CVE-2026-89750","ts":1789356676806,"field":"severity","old":"high","new":"medium"},{"seq":153638,"id":"CVE-2026-89750","ts":1789285351659,"field":"cvss","old":null,"new":"7.8"},{"seq":153637,"id":"CVE-2026-89750","ts":1789285351659,"field":"severity","old":"none","new":"high"},{"seq":147492,"id":"CVE-2026-89750","ts":1789270211121,"field":"cvss","old":null,"new":"4.7"},{"seq":147491,"id":"CVE-2026-89750","ts":1789270211121,"field":"severity","old":"none","new":"medium"},{"seq":109244,"id":"CVE-2026-89750","ts":1789183731121,"field":"cvss","old":null,"new":"4.7"},{"seq":109243,"id":"CVE-2026-89750","ts":1789183731121,"field":"severity","old":"none","new":"medium"}]}