{"id":"CVE-2025-38017","url":"https://www.cyber-defence.io/tools/cve/CVE-2025-38017","generatedAt":"2026-10-28T02:13:05.915Z","title":"In the Linux kernel, the following vulnerability has been resolved: fs/eventpoll: fix endless busy loop after timeout has expired After commit 0a65bc27bd64 (\"eventpoll: Set epoll timeout if it's in the future\"), the following program would immediately…","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nfs/eventpoll: fix endless busy loop after timeout has expired\n\nAfter commit 0a65bc27bd64 (\"eventpoll: Set epoll timeout if it's in\nthe future\"), the following program would immediately enter a busy\nloop in the kernel:\n\n```\nint main() {\n  int e = epoll_create1(0);\n  struct epoll_event event = {.events = EPOLLIN};\n  epoll_ctl(e, EPOLL_CTL_ADD, 0, &event);\n  const struct timespec timeout = {.tv_nsec = 1};\n  epoll_pwait2(e, &event, 1, &timeout, 0);\n}\n```\n\nThis happens because the given (non-zero) timeout of 1 nanosecond\nusually expires before ep_poll() is entered and then\nep_schedule_timeout() returns false, but `timed_out` is never set\nbecause the code line that sets it is skipped.  This quickly turns\ninto a soft lockup, RCU stalls and deadlocks, inflicting severe\nheadaches to the whole system.\n\nWhen the timeout has expired, we don't need to schedule a hrtimer, but\nwe should set the `timed_out` variable.  Therefore, I suggest moving\nthe ep_schedule_timeout() check into the `timed_out` expression\ninstead of skipping it.\n\nbrauner: Note that there was an earlier fix by Joe Damato in response to\nmy bug report in [1].","published":"2025-06-18T10:15:33.000Z","lastModified":"2026-06-17T09:15:53.000Z","status":"Analyzed","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","score":5.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"},"cwe":[],"affected":["linux/linux kernel"],"epss":{"score":0.00163,"percentile":0.05469,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.16%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/7631dca012593c95d36199082546a24a0058fc50","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d9ec73301099ec5975505e1c3effbe768bab9490","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2025-38017","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}