{"id":"CVE-2026-46242","title":"In the Linux kernel, the following vulnerability has been resolved:\n\neventpoll: fix ep_remove struct eventpoll / struct file UAF\n\nep_remove() (via ep_remove_file()) cleared file->f_ep under\nfile->f_lock but then kept using @file inside t…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\neventpoll: fix ep_remove struct eventpoll / struct file UAF\n\nep_remove() (via ep_remove_file()) cleared file->f_ep under\nfile->f_lock but then kept using @file inside t…","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","cwe":["CWE-416"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 5.15.209, < 5.16","linux_kernel >= 6.1.175, < 6.2","linux_kernel >= 6.4, < 6.18.33","linux_kernel >= 6.19, < 7.0.10"],"patched":["linux_kernel 7.0.10"],"published":"2026-05-30","updated":"2026-07-04","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-46242","references":[{"url":"https://git.kernel.org/stable/c/2de4db145b2992da496fea6c51f9839be678ae24","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9324de74a3a59b9fde9b62ee45ebaa71458ba2e5","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a6dc643c69311677c574a0f17a3f4d66a5f3744b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ced39b6a8062bac5c18a1c3df85634107eb8664a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ef4ca02e95363e78977ca04340d44fe3b4b2b81f","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","exploit-available"],"epss":0.03153,"epssPercentile":0.87408,"ingestedAt":"2026-07-04T12:56:09.573Z","exploits":{"github":4,"githubRepos":["https://github.com/0xBlackash/CVE-2026-46242","https://github.com/SaithFranklinB/ScannerBadEpoll","https://github.com/Baba01hacker666/CVE-2026-46242"],"checkedAt":"2026-09-24T07:53:04.294Z"},"exploitAvailable":true,"slug":"CVE-2026-46242","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\neventpoll: fix ep_remove struct eventpoll / struct file UAF\n\nep_remove() (via ep_remove_file()) cleared file->f_ep under\nfile->f_lock but then kept using @file inside the critical section\n(is_file_epoll(), hlist_del_rcu() through the head, spin_unlock).\nA concurrent __fput() taking the eventpoll_release() fastpath in\nthat window observed the transient NULL, skipped\neventpoll_release_file() and ran to f_op->release / file_free().\n\nFor the epoll-watches-epoll case, f_op->release is\nep_eventpoll_release() -> ep_clear_and_put() -> ep_free(), which\nkfree()s the watched struct eventpoll. Its embedded ->refs\nhlist_head is exactly where epi->fllink.pprev points, so the\nsubsequent hlist_del_rcu()'s \"*pprev = next\" scribbles into freed\nkmalloc-192 memory.\n\nIn addition, struct file is SLAB_TYPESAFE_BY_RCU, so the slot\nbacking @file could be recycled by alloc_empty_file() --\nreinitializing f_lock and f_ep -- while ep_remove() is still\nnominally inside that lock. The upshot is an attacker-controllable\nkmem_cache_free() against the wrong slab cache.\n\nPin @file via epi_fget() at the top of ep_remove() and gate the\ncritical section on the pin succeeding. With the pin held @file\ncannot reach refcount zero, which holds __fput() off and\ntransitively keeps the watched struct eventpoll alive across the\nhlist_del_rcu() and the f_lock use, closing both UAFs.\n\nIf the pin fails @file has already reached refcount zero and its\n__fput() is in flight. Because we bailed before clearing f_ep,\nthat path takes the eventpoll_release() slow path into\neventpoll_release_file() and blocks on ep->mtx until the waiter\nside's ep_clear_and_put() drops it. The bailed epi's share of\nep->refcount stays intact, so the trailing ep_refcount_dec_and_test()\nin ep_clear_and_put() cannot free the eventpoll out from under\neventpoll_release_file(); the orphaned epi is then cleaned up\nthere.\n\nA successful pin also proves we are not racing\neventpoll_release_file() on this epi, so drop the now-redundant\nre-check of epi->dying under f_lock. The cheap lockless\nREAD_ONCE(epi->dying) fast-path bailout stays.\n\n## Affected\n\n- `linux_kernel >= 5.15.209, < 5.16`\n- `linux_kernel >= 6.1.175, < 6.2`\n- `linux_kernel >= 6.4, < 6.18.33`\n- `linux_kernel >= 6.19, < 7.0.10`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 7.0.10`","depth":"midnight","depthScore":56,"depthScoreParts":{"impact":42.9,"likelihood":0.6,"exploitation":12,"ransomware":0},"changes":[{"seq":5246,"id":"CVE-2026-46242","ts":1788887256556,"field":"exploit_available","old":"false","new":"true"},{"seq":4129,"id":"CVE-2026-46242","ts":1788886372953,"field":"exploit_available","old":"true","new":"false"},{"seq":2902,"id":"CVE-2026-46242","ts":1788883038894,"field":"exploit_available","old":"false","new":"true"},{"seq":1931,"id":"CVE-2026-46242","ts":1788882441907,"field":"exploit_available","old":"true","new":"false"},{"seq":1020,"id":"CVE-2026-46242","ts":1788881876644,"field":"exploit_available","old":"false","new":"true"}]}