{"api_version":"1","generated_at":"2026-11-06T18:31:08+00:00","cve":"CVE-2026-99255","urls":{"html":"https://cve.report/CVE-2026-99255","api":"https://cve.report/api/cve/CVE-2026-99255.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-99255","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-99255"},"summary":{"title":"io_uring/io-wq: don't hide a link from cancellations","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/io-wq: don't hide a link from cancellations\n\nA task that exits cancels its tracked requests and waits until they are\ngone. io_uring_cancel_generic() looks everywhere a request can be, and\ngoes to sleep if it found nothing to cancel. It is woken up each time\none of the requests of the task is completed by task work or freed.\n\nWhen io-wq is done with a request that has a link, there is a time in which\nthe next request of the link can't be found:\n\n  io_worker_handle_work()\n    io_assign_current_work(worker, NULL)\n    io_wq_free_work(work)\n      io_req_find_next()           // takes the link off the request\n      io_free_req()                // task work for the task\n    io_assign_current_work(worker, linked)\n      io_run_task_work()\n      cond_resched()\n      worker->cur_work = linked\n\nIt is not pending, it is not the current work of a worker, and it is not\nyet on the list that it is about to be parked on. If the pass that the\nexiting task makes because of io_free_req() falls into that time, it finds\nnothing and the task goes to sleep. The worker then runs the link, which\nIO_WQ_BIT_EXIT doesn't prevent for bounded work. If that parks the request\nnothing is completed or freed, and nobody wakes up the task. If it is the\nprocess that exits it can't be killed any more either.\n\n  NOP, IOSQE_ASYNC | IOSQE_IO_LINK\n  FUTEX_WAIT, FUTEX2_PRIVATE\n  exit of the thread, or of the process, up to 63us later\n\nWith four of these per round 5 to 8 of 10,000 rounds hang (4 CPUs, KVM):\n\n  io_uring_cancel_generic\n  do_exit\n\nCommit f8b632e89a10 (\"io_uring: tighten task exit cancellations\") is about\nthe same gap, and makes the task look again for whatever happens before\nio_free_req().\n\nFree the request once the link is the current work of the worker, or\npending. Whoever is woken up by that can find the link, until it is parked\nwhere cancellations look as well. To do so split io_wq_free_work() in two.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-11-03 12:17:32","updated_at":"2026-11-06 18:18:33"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/59e45f44c3cea9f4b2d099171c3cec1d25c5b638","name":"https://git.kernel.org/stable/c/59e45f44c3cea9f4b2d099171c3cec1d25c5b638","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/436d48a2ed13112d2d27085325838e5bce6b4507","name":"https://git.kernel.org/stable/c/436d48a2ed13112d2d27085325838e5bce6b4507","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/92e20e9c72bdf6cfa6f84eded7b33399bc7061da","name":"https://git.kernel.org/stable/c/92e20e9c72bdf6cfa6f84eded7b33399bc7061da","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d39ebc7a583d650b1d6da9b45e2ce96ad4d877e4","name":"https://git.kernel.org/stable/c/d39ebc7a583d650b1d6da9b45e2ce96ad4d877e4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3e02b8df0e9fa1423ac2a4e03409a9329c30ac49","name":"https://git.kernel.org/stable/c/3e02b8df0e9fa1423ac2a4e03409a9329c30ac49","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/ebe8e97fb99d9f374c482902a00677cfd24a6c27","name":"https://git.kernel.org/stable/c/ebe8e97fb99d9f374c482902a00677cfd24a6c27","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/98470f164286f7f62aaee519d4d11b9370ce6d7b","name":"https://git.kernel.org/stable/c/98470f164286f7f62aaee519d4d11b9370ce6d7b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-99255","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99255","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 768134d4f48109b90f4248feecbeeb7d684e410c 98470f164286f7f62aaee519d4d11b9370ce6d7b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 768134d4f48109b90f4248feecbeeb7d684e410c d39ebc7a583d650b1d6da9b45e2ce96ad4d877e4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 768134d4f48109b90f4248feecbeeb7d684e410c ebe8e97fb99d9f374c482902a00677cfd24a6c27 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 768134d4f48109b90f4248feecbeeb7d684e410c 3e02b8df0e9fa1423ac2a4e03409a9329c30ac49 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 768134d4f48109b90f4248feecbeeb7d684e410c 92e20e9c72bdf6cfa6f84eded7b33399bc7061da git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 768134d4f48109b90f4248feecbeeb7d684e410c 59e45f44c3cea9f4b2d099171c3cec1d25c5b638 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 768134d4f48109b90f4248feecbeeb7d684e410c 436d48a2ed13112d2d27085325838e5bce6b4507 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.5","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.5 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.191 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.161 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.115 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.60 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.14 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3.2 7.3.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.4-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["io_uring/io-wq.c","io_uring/io_uring.c","io_uring/io_uring.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"98470f164286f7f62aaee519d4d11b9370ce6d7b","status":"affected","version":"768134d4f48109b90f4248feecbeeb7d684e410c","versionType":"git"},{"lessThan":"d39ebc7a583d650b1d6da9b45e2ce96ad4d877e4","status":"affected","version":"768134d4f48109b90f4248feecbeeb7d684e410c","versionType":"git"},{"lessThan":"ebe8e97fb99d9f374c482902a00677cfd24a6c27","status":"affected","version":"768134d4f48109b90f4248feecbeeb7d684e410c","versionType":"git"},{"lessThan":"3e02b8df0e9fa1423ac2a4e03409a9329c30ac49","status":"affected","version":"768134d4f48109b90f4248feecbeeb7d684e410c","versionType":"git"},{"lessThan":"92e20e9c72bdf6cfa6f84eded7b33399bc7061da","status":"affected","version":"768134d4f48109b90f4248feecbeeb7d684e410c","versionType":"git"},{"lessThan":"59e45f44c3cea9f4b2d099171c3cec1d25c5b638","status":"affected","version":"768134d4f48109b90f4248feecbeeb7d684e410c","versionType":"git"},{"lessThan":"436d48a2ed13112d2d27085325838e5bce6b4507","status":"affected","version":"768134d4f48109b90f4248feecbeeb7d684e410c","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["io_uring/io-wq.c","io_uring/io_uring.c","io_uring/io_uring.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.5"},{"lessThan":"5.5","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.191","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.161","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.115","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.60","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.14","versionType":"semver"},{"lessThanOrEqual":"7.3.*","status":"unaffected","version":"7.3.2","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.4-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.191","versionStartIncluding":"5.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.161","versionStartIncluding":"5.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.115","versionStartIncluding":"5.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.60","versionStartIncluding":"5.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.14","versionStartIncluding":"5.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3.2","versionStartIncluding":"5.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.4-rc1","versionStartIncluding":"5.5","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/io-wq: don't hide a link from cancellations\n\nA task that exits cancels its tracked requests and waits until they are\ngone. io_uring_cancel_generic() looks everywhere a request can be, and\ngoes to sleep if it found nothing to cancel. It is woken up each time\none of the requests of the task is completed by task work or freed.\n\nWhen io-wq is done with a request that has a link, there is a time in which\nthe next request of the link can't be found:\n\n  io_worker_handle_work()\n    io_assign_current_work(worker, NULL)\n    io_wq_free_work(work)\n      io_req_find_next()           // takes the link off the request\n      io_free_req()                // task work for the task\n    io_assign_current_work(worker, linked)\n      io_run_task_work()\n      cond_resched()\n      worker->cur_work = linked\n\nIt is not pending, it is not the current work of a worker, and it is not\nyet on the list that it is about to be parked on. If the pass that the\nexiting task makes because of io_free_req() falls into that time, it finds\nnothing and the task goes to sleep. The worker then runs the link, which\nIO_WQ_BIT_EXIT doesn't prevent for bounded work. If that parks the request\nnothing is completed or freed, and nobody wakes up the task. If it is the\nprocess that exits it can't be killed any more either.\n\n  NOP, IOSQE_ASYNC | IOSQE_IO_LINK\n  FUTEX_WAIT, FUTEX2_PRIVATE\n  exit of the thread, or of the process, up to 63us later\n\nWith four of these per round 5 to 8 of 10,000 rounds hang (4 CPUs, KVM):\n\n  io_uring_cancel_generic\n  do_exit\n\nCommit f8b632e89a10 (\"io_uring: tighten task exit cancellations\") is about\nthe same gap, and makes the task look again for whatever happens before\nio_free_req().\n\nFree the request once the link is the current work of the worker, or\npending. Whoever is woken up by that can find the link, until it is parked\nwhere cancellations look as well. To do so split io_wq_free_work() in two."}],"providerMetadata":{"dateUpdated":"2026-11-06T17:15:13.796Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/98470f164286f7f62aaee519d4d11b9370ce6d7b"},{"url":"https://git.kernel.org/stable/c/d39ebc7a583d650b1d6da9b45e2ce96ad4d877e4"},{"url":"https://git.kernel.org/stable/c/ebe8e97fb99d9f374c482902a00677cfd24a6c27"},{"url":"https://git.kernel.org/stable/c/3e02b8df0e9fa1423ac2a4e03409a9329c30ac49"},{"url":"https://git.kernel.org/stable/c/92e20e9c72bdf6cfa6f84eded7b33399bc7061da"},{"url":"https://git.kernel.org/stable/c/59e45f44c3cea9f4b2d099171c3cec1d25c5b638"},{"url":"https://git.kernel.org/stable/c/436d48a2ed13112d2d27085325838e5bce6b4507"}],"title":"io_uring/io-wq: don't hide a link from cancellations","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-99255","datePublished":"2026-11-03T11:20:13.169Z","dateReserved":"2026-09-25T10:25:14.404Z","dateUpdated":"2026-11-06T17:15:13.796Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-11-03 12:17:32","lastModifiedDate":"2026-11-06 18:18:33","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"99255","Ordinal":"1","Title":"io_uring/io-wq: don't hide a link from cancellations","CVE":"CVE-2026-99255","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"99255","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/io-wq: don't hide a link from cancellations\n\nA task that exits cancels its tracked requests and waits until they are\ngone. io_uring_cancel_generic() looks everywhere a request can be, and\ngoes to sleep if it found nothing to cancel. It is woken up each time\none of the requests of the task is completed by task work or freed.\n\nWhen io-wq is done with a request that has a link, there is a time in which\nthe next request of the link can't be found:\n\n  io_worker_handle_work()\n    io_assign_current_work(worker, NULL)\n    io_wq_free_work(work)\n      io_req_find_next()           // takes the link off the request\n      io_free_req()                // task work for the task\n    io_assign_current_work(worker, linked)\n      io_run_task_work()\n      cond_resched()\n      worker->cur_work = linked\n\nIt is not pending, it is not the current work of a worker, and it is not\nyet on the list that it is about to be parked on. If the pass that the\nexiting task makes because of io_free_req() falls into that time, it finds\nnothing and the task goes to sleep. The worker then runs the link, which\nIO_WQ_BIT_EXIT doesn't prevent for bounded work. If that parks the request\nnothing is completed or freed, and nobody wakes up the task. If it is the\nprocess that exits it can't be killed any more either.\n\n  NOP, IOSQE_ASYNC | IOSQE_IO_LINK\n  FUTEX_WAIT, FUTEX2_PRIVATE\n  exit of the thread, or of the process, up to 63us later\n\nWith four of these per round 5 to 8 of 10,000 rounds hang (4 CPUs, KVM):\n\n  io_uring_cancel_generic\n  do_exit\n\nCommit f8b632e89a10 (\"io_uring: tighten task exit cancellations\") is about\nthe same gap, and makes the task look again for whatever happens before\nio_free_req().\n\nFree the request once the link is the current work of the worker, or\npending. Whoever is woken up by that can find the link, until it is parked\nwhere cancellations look as well. To do so split io_wq_free_work() in two.","Type":"Description","Title":"io_uring/io-wq: don't hide a link from cancellations"}]}}}