{"api_version":"1","generated_at":"2026-11-06T18:31:09+00:00","cve":"CVE-2026-99254","urls":{"html":"https://cve.report/CVE-2026-99254","api":"https://cve.report/api/cve/CVE-2026-99254.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-99254","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-99254"},"summary":{"title":"io_uring: don't flood a cancelling task with task_work","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring: don't flood a cancelling task with task_work\n\nio_ring_exit_work() asks each task which has used the ring to remove its\ntctx node, by task_work, and repeats that until the list is empty.\nio_tctx_exit_cb() doesn't touch the node while the task is in\nio_uring_cancel_generic(), which removes all the nodes at its end. So the\nwork item queues the callback again as soon as it has completed, for\nnothing.\n\nThat is more than a waste of time. task_work_run() only returns when it\nfinds the list empty. If the rings are released from inside the\ncancellation, because requests of other rings held the last references to\ntheir files, up to 64 work items keep sending callbacks to the one task\nwhich is running them. It never finds the list empty, never gets back to\nthe cancellation, the nodes stay, and so it goes on: a task with 60 pairs\nof rings which poll each other ran 280000 callbacks in 5 seconds, 20\nseconds after exit_group(). It ends when all the senders happen to be late\nat the same time. Until then the task keeps a CPU and the work items busy.\n\nAn exiting task can't be killed meanwhile. execve() cancels the requests in\nthe same way, so a live task can get stuck there as well, for minutes. If\nit takes more than five, the work items run into the\nWARN_ON_ONCE(time_after(jiffies, timeout)) of io_ring_exit_work(). No\nprivilege is needed for any of this.\n\nIf the callback has met a task in cancellation, wait a little before it is\nsent again. Nobody has to wake the work item up for that: either the node\nis gone by then, or it is the turn of the next round.","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/a22fb44e988b01b82235ea07f0bf0fc73e256596","name":"https://git.kernel.org/stable/c/a22fb44e988b01b82235ea07f0bf0fc73e256596","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2c75ebae8a7f09c99e31c7042b7d4d595f03b2b1","name":"https://git.kernel.org/stable/c/2c75ebae8a7f09c99e31c7042b7d4d595f03b2b1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/14f56e9c0b8fdc2e178acdbec9781e90ef46f7e9","name":"https://git.kernel.org/stable/c/14f56e9c0b8fdc2e178acdbec9781e90ef46f7e9","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f334e79a11e084713e82402b1a7a0e321526992a","name":"https://git.kernel.org/stable/c/f334e79a11e084713e82402b1a7a0e321526992a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/22e643e61b9b6299b42ff7d88bab48bccada8a5d","name":"https://git.kernel.org/stable/c/22e643e61b9b6299b42ff7d88bab48bccada8a5d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/61c761fc21e00e45c33c2bb596be442d92fb8792","name":"https://git.kernel.org/stable/c/61c761fc21e00e45c33c2bb596be442d92fb8792","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/abdc57c7ebabaaf0b622178a6a85834e1e54ff80","name":"https://git.kernel.org/stable/c/abdc57c7ebabaaf0b622178a6a85834e1e54ff80","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-99254","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99254","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d56d938b4bef3e1421a42023cdcd6e13c1f50831 a22fb44e988b01b82235ea07f0bf0fc73e256596 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d56d938b4bef3e1421a42023cdcd6e13c1f50831 2c75ebae8a7f09c99e31c7042b7d4d595f03b2b1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d56d938b4bef3e1421a42023cdcd6e13c1f50831 61c761fc21e00e45c33c2bb596be442d92fb8792 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d56d938b4bef3e1421a42023cdcd6e13c1f50831 14f56e9c0b8fdc2e178acdbec9781e90ef46f7e9 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d56d938b4bef3e1421a42023cdcd6e13c1f50831 abdc57c7ebabaaf0b622178a6a85834e1e54ff80 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d56d938b4bef3e1421a42023cdcd6e13c1f50831 f334e79a11e084713e82402b1a7a0e321526992a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d56d938b4bef3e1421a42023cdcd6e13c1f50831 22e643e61b9b6299b42ff7d88bab48bccada8a5d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.12","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.12 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_uring.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"a22fb44e988b01b82235ea07f0bf0fc73e256596","status":"affected","version":"d56d938b4bef3e1421a42023cdcd6e13c1f50831","versionType":"git"},{"lessThan":"2c75ebae8a7f09c99e31c7042b7d4d595f03b2b1","status":"affected","version":"d56d938b4bef3e1421a42023cdcd6e13c1f50831","versionType":"git"},{"lessThan":"61c761fc21e00e45c33c2bb596be442d92fb8792","status":"affected","version":"d56d938b4bef3e1421a42023cdcd6e13c1f50831","versionType":"git"},{"lessThan":"14f56e9c0b8fdc2e178acdbec9781e90ef46f7e9","status":"affected","version":"d56d938b4bef3e1421a42023cdcd6e13c1f50831","versionType":"git"},{"lessThan":"abdc57c7ebabaaf0b622178a6a85834e1e54ff80","status":"affected","version":"d56d938b4bef3e1421a42023cdcd6e13c1f50831","versionType":"git"},{"lessThan":"f334e79a11e084713e82402b1a7a0e321526992a","status":"affected","version":"d56d938b4bef3e1421a42023cdcd6e13c1f50831","versionType":"git"},{"lessThan":"22e643e61b9b6299b42ff7d88bab48bccada8a5d","status":"affected","version":"d56d938b4bef3e1421a42023cdcd6e13c1f50831","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["io_uring/io_uring.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.12"},{"lessThan":"5.12","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":"5.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.161","versionStartIncluding":"5.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.115","versionStartIncluding":"5.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.60","versionStartIncluding":"5.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.14","versionStartIncluding":"5.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3.2","versionStartIncluding":"5.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.4-rc1","versionStartIncluding":"5.12","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring: don't flood a cancelling task with task_work\n\nio_ring_exit_work() asks each task which has used the ring to remove its\ntctx node, by task_work, and repeats that until the list is empty.\nio_tctx_exit_cb() doesn't touch the node while the task is in\nio_uring_cancel_generic(), which removes all the nodes at its end. So the\nwork item queues the callback again as soon as it has completed, for\nnothing.\n\nThat is more than a waste of time. task_work_run() only returns when it\nfinds the list empty. If the rings are released from inside the\ncancellation, because requests of other rings held the last references to\ntheir files, up to 64 work items keep sending callbacks to the one task\nwhich is running them. It never finds the list empty, never gets back to\nthe cancellation, the nodes stay, and so it goes on: a task with 60 pairs\nof rings which poll each other ran 280000 callbacks in 5 seconds, 20\nseconds after exit_group(). It ends when all the senders happen to be late\nat the same time. Until then the task keeps a CPU and the work items busy.\n\nAn exiting task can't be killed meanwhile. execve() cancels the requests in\nthe same way, so a live task can get stuck there as well, for minutes. If\nit takes more than five, the work items run into the\nWARN_ON_ONCE(time_after(jiffies, timeout)) of io_ring_exit_work(). No\nprivilege is needed for any of this.\n\nIf the callback has met a task in cancellation, wait a little before it is\nsent again. Nobody has to wake the work item up for that: either the node\nis gone by then, or it is the turn of the next round."}],"providerMetadata":{"dateUpdated":"2026-11-06T17:15:13.328Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/a22fb44e988b01b82235ea07f0bf0fc73e256596"},{"url":"https://git.kernel.org/stable/c/2c75ebae8a7f09c99e31c7042b7d4d595f03b2b1"},{"url":"https://git.kernel.org/stable/c/61c761fc21e00e45c33c2bb596be442d92fb8792"},{"url":"https://git.kernel.org/stable/c/14f56e9c0b8fdc2e178acdbec9781e90ef46f7e9"},{"url":"https://git.kernel.org/stable/c/abdc57c7ebabaaf0b622178a6a85834e1e54ff80"},{"url":"https://git.kernel.org/stable/c/f334e79a11e084713e82402b1a7a0e321526992a"},{"url":"https://git.kernel.org/stable/c/22e643e61b9b6299b42ff7d88bab48bccada8a5d"}],"title":"io_uring: don't flood a cancelling task with task_work","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-99254","datePublished":"2026-11-03T11:20:12.802Z","dateReserved":"2026-09-25T10:25:14.403Z","dateUpdated":"2026-11-06T17:15:13.328Z","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":"99254","Ordinal":"1","Title":"io_uring: don't flood a cancelling task with task_work","CVE":"CVE-2026-99254","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"99254","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring: don't flood a cancelling task with task_work\n\nio_ring_exit_work() asks each task which has used the ring to remove its\ntctx node, by task_work, and repeats that until the list is empty.\nio_tctx_exit_cb() doesn't touch the node while the task is in\nio_uring_cancel_generic(), which removes all the nodes at its end. So the\nwork item queues the callback again as soon as it has completed, for\nnothing.\n\nThat is more than a waste of time. task_work_run() only returns when it\nfinds the list empty. If the rings are released from inside the\ncancellation, because requests of other rings held the last references to\ntheir files, up to 64 work items keep sending callbacks to the one task\nwhich is running them. It never finds the list empty, never gets back to\nthe cancellation, the nodes stay, and so it goes on: a task with 60 pairs\nof rings which poll each other ran 280000 callbacks in 5 seconds, 20\nseconds after exit_group(). It ends when all the senders happen to be late\nat the same time. Until then the task keeps a CPU and the work items busy.\n\nAn exiting task can't be killed meanwhile. execve() cancels the requests in\nthe same way, so a live task can get stuck there as well, for minutes. If\nit takes more than five, the work items run into the\nWARN_ON_ONCE(time_after(jiffies, timeout)) of io_ring_exit_work(). No\nprivilege is needed for any of this.\n\nIf the callback has met a task in cancellation, wait a little before it is\nsent again. Nobody has to wake the work item up for that: either the node\nis gone by then, or it is the turn of the next round.","Type":"Description","Title":"io_uring: don't flood a cancelling task with task_work"}]}}}