{"api_version":"1","generated_at":"2026-11-10T18:03:37+00:00","cve":"CVE-2026-99140","urls":{"html":"https://cve.report/CVE-2026-99140","api":"https://cve.report/api/cve/CVE-2026-99140.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-99140","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-99140"},"summary":{"title":"tracing: Fix hist trigger timestamps for buffered events","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix hist trigger timestamps for buffered events\n\nSyzkaller triggered a WARN_ON_ONCE(!nest) warning:\n\n  WARNING: kernel/trace/ring_buffer.c:821 at ring_buffer_event_time_stamp\n  Call trace:\n    ring_buffer_event_time_stamp\n    hist_field_timestamp\n    hist_fn_call\n    event_hist_trigger\n    event_triggers_call\n    __event_trigger_test_discard\n    trace_event_buffer_commit\n    do_trace_event_raw_event_sched_switch\n    trace_event_raw_event_sched_switch\n\nThe warning is probabilistically reproducible and is related to syzkaller\nexecuting the following commands:\n\n  echo 'prev_pid == 999999' > events/sched/sched_switch/filter\n  echo 'hist:keys=common_timestamp' > events/sched/sched_switch/trigger\n\nThe specific triggering process is as follows:\n\nCPU 0                                           CPU 1\n(context switching)                             (echo 'hist:keys=common_timestamp' > \\\n                                                        events/sched/sched_switch/trigger)\ndo_trace_event_raw_event_##call\n  trace_event_buffer_lock_reserve\n    if (!tr->no_filter_buffering_ref &&\n        trace_file->flags & EVENT_FILE_FL_FILTERED)\n        return entry;  // return directly\n                                                event_hist_trigger_parse\n                                                  hist_register_trigger\n                                                    tracing_set_filter_buffering(file->tr, true);\n                                                      tr->no_filter_buffering_ref++;\n    __trace_buffer_lock_reserve\n      rb_start_commit\n        local_inc(&cpu_buffer->committing);  // skipped and not executed\n  trace_event_buffer_commit\n    __event_trigger_test_discard\n      event_triggers_call\n        event_hist_trigger\n          hist_fn_call\n            hist_field_timestamp\n              ring_buffer_event_time_stamp\n                nest = local_read(&cpu_buffer->committing);\n                WARN_ON_ONCE(!nest)  // trigger warning\n\nThe root cause is that when an event file has a filter attached and the\nhist trigger has not yet been attached, trace_event_buffer_lock_reserve()\nwrites the event into the per-CPU trace_buffered_event temp buffer instead\nof reserving it in the ring buffer, so cpu_buffer->committing is not\nincremented. When the event is later processed at commit time by a hist\ntrigger, hist_field_timestamp() -> ring_buffer_event_time_stamp() sees a\nzero committing count, triggering WARN_ON_ONCE(!nest).\n\ntracing_event_time_stamp() was added by commit d8279bfc5e959 (\"tracing:\nAdd tracing_event_time_stamp() API\") for exactly this case: if the event\nis the per-CPU trace_buffered_event, it returns the current ring buffer\ntimestamp. But it never gained a caller. Use it in hist_field_timestamp(),\nso that a hist trigger that races onto a buffered event records the\ncurrent time, which is only marginally later than when the event was\nrecorded, instead of warning and recording a bogus timestamp.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-28 11:17:33","updated_at":"2026-10-30 13:21:48"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/09c7cce2e59e6b3b1807520bcb1980c561f15d1e","name":"https://git.kernel.org/stable/c/09c7cce2e59e6b3b1807520bcb1980c561f15d1e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/9414ca3b99e5a7f1f3bf51c2a01b383e1b355dd0","name":"https://git.kernel.org/stable/c/9414ca3b99e5a7f1f3bf51c2a01b383e1b355dd0","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/af192a356e9830a0df231b590ad6fb1fc28c9315","name":"https://git.kernel.org/stable/c/af192a356e9830a0df231b590ad6fb1fc28c9315","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b3a94a79047d3fc9385b3709cb2b86f4a26ed0c3","name":"https://git.kernel.org/stable/c/b3a94a79047d3fc9385b3709cb2b86f4a26ed0c3","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/89e90b16aadd6e66bd0323bc8dfc76a62e756b57","name":"https://git.kernel.org/stable/c/89e90b16aadd6e66bd0323bc8dfc76a62e756b57","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/71c5c7420478d94d6eb0b427f66fa41bbda651e3","name":"https://git.kernel.org/stable/c/71c5c7420478d94d6eb0b427f66fa41bbda651e3","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/ab320f6aa3769480f735ed0ad026c4a61799b7bc","name":"https://git.kernel.org/stable/c/ab320f6aa3769480f735ed0ad026c4a61799b7bc","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-99140","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99140","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b94bc80df64823e676b506f8de7dcf6a688d681e b3a94a79047d3fc9385b3709cb2b86f4a26ed0c3 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b94bc80df64823e676b506f8de7dcf6a688d681e 71c5c7420478d94d6eb0b427f66fa41bbda651e3 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b94bc80df64823e676b506f8de7dcf6a688d681e ab320f6aa3769480f735ed0ad026c4a61799b7bc git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b94bc80df64823e676b506f8de7dcf6a688d681e af192a356e9830a0df231b590ad6fb1fc28c9315 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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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 6.18.59 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.13 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"99140","cve":"CVE-2026-99140","epss":"0.001730000","percentile":"0.067370000","score_date":"2026-11-01","updated_at":"2026-11-02 00:05:55"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["kernel/trace/trace_events_hist.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"b3a94a79047d3fc9385b3709cb2b86f4a26ed0c3","status":"affected","version":"b94bc80df64823e676b506f8de7dcf6a688d681e","versionType":"git"},{"lessThan":"71c5c7420478d94d6eb0b427f66fa41bbda651e3","status":"affected","version":"b94bc80df64823e676b506f8de7dcf6a688d681e","versionType":"git"},{"lessThan":"ab320f6aa3769480f735ed0ad026c4a61799b7bc","status":"affected","version":"b94bc80df64823e676b506f8de7dcf6a688d681e","versionType":"git"},{"lessThan":"af192a356e9830a0df231b590ad6fb1fc28c9315","status":"affected","version":"b94bc80df64823e676b506f8de7dcf6a688d681e","versionType":"git"},{"lessThan":"09c7cce2e59e6b3b1807520bcb1980c561f15d1e","status":"affected","version":"b94bc80df64823e676b506f8de7dcf6a688d681e","versionType":"git"},{"lessThan":"89e90b16aadd6e66bd0323bc8dfc76a62e756b57","status":"affected","version":"b94bc80df64823e676b506f8de7dcf6a688d681e","versionType":"git"},{"lessThan":"9414ca3b99e5a7f1f3bf51c2a01b383e1b355dd0","status":"affected","version":"b94bc80df64823e676b506f8de7dcf6a688d681e","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["kernel/trace/trace_events_hist.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.13"},{"lessThan":"5.13","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.224","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":"6.18.59","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.13","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.224","versionStartIncluding":"5.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.191","versionStartIncluding":"5.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.161","versionStartIncluding":"5.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.115","versionStartIncluding":"5.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.59","versionStartIncluding":"5.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.13","versionStartIncluding":"5.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"5.13","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix hist trigger timestamps for buffered events\n\nSyzkaller triggered a WARN_ON_ONCE(!nest) warning:\n\n  WARNING: kernel/trace/ring_buffer.c:821 at ring_buffer_event_time_stamp\n  Call trace:\n    ring_buffer_event_time_stamp\n    hist_field_timestamp\n    hist_fn_call\n    event_hist_trigger\n    event_triggers_call\n    __event_trigger_test_discard\n    trace_event_buffer_commit\n    do_trace_event_raw_event_sched_switch\n    trace_event_raw_event_sched_switch\n\nThe warning is probabilistically reproducible and is related to syzkaller\nexecuting the following commands:\n\n  echo 'prev_pid == 999999' > events/sched/sched_switch/filter\n  echo 'hist:keys=common_timestamp' > events/sched/sched_switch/trigger\n\nThe specific triggering process is as follows:\n\nCPU 0                                           CPU 1\n(context switching)                             (echo 'hist:keys=common_timestamp' > \\\n                                                        events/sched/sched_switch/trigger)\ndo_trace_event_raw_event_##call\n  trace_event_buffer_lock_reserve\n    if (!tr->no_filter_buffering_ref &&\n        trace_file->flags & EVENT_FILE_FL_FILTERED)\n        return entry;  // return directly\n                                                event_hist_trigger_parse\n                                                  hist_register_trigger\n                                                    tracing_set_filter_buffering(file->tr, true);\n                                                      tr->no_filter_buffering_ref++;\n    __trace_buffer_lock_reserve\n      rb_start_commit\n        local_inc(&cpu_buffer->committing);  // skipped and not executed\n  trace_event_buffer_commit\n    __event_trigger_test_discard\n      event_triggers_call\n        event_hist_trigger\n          hist_fn_call\n            hist_field_timestamp\n              ring_buffer_event_time_stamp\n                nest = local_read(&cpu_buffer->committing);\n                WARN_ON_ONCE(!nest)  // trigger warning\n\nThe root cause is that when an event file has a filter attached and the\nhist trigger has not yet been attached, trace_event_buffer_lock_reserve()\nwrites the event into the per-CPU trace_buffered_event temp buffer instead\nof reserving it in the ring buffer, so cpu_buffer->committing is not\nincremented. When the event is later processed at commit time by a hist\ntrigger, hist_field_timestamp() -> ring_buffer_event_time_stamp() sees a\nzero committing count, triggering WARN_ON_ONCE(!nest).\n\ntracing_event_time_stamp() was added by commit d8279bfc5e959 (\"tracing:\nAdd tracing_event_time_stamp() API\") for exactly this case: if the event\nis the per-CPU trace_buffered_event, it returns the current ring buffer\ntimestamp. But it never gained a caller. Use it in hist_field_timestamp(),\nso that a hist trigger that races onto a buffered event records the\ncurrent time, which is only marginally later than when the event was\nrecorded, instead of warning and recording a bogus timestamp."}],"providerMetadata":{"dateUpdated":"2026-10-30T12:42:12.896Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/b3a94a79047d3fc9385b3709cb2b86f4a26ed0c3"},{"url":"https://git.kernel.org/stable/c/71c5c7420478d94d6eb0b427f66fa41bbda651e3"},{"url":"https://git.kernel.org/stable/c/ab320f6aa3769480f735ed0ad026c4a61799b7bc"},{"url":"https://git.kernel.org/stable/c/af192a356e9830a0df231b590ad6fb1fc28c9315"},{"url":"https://git.kernel.org/stable/c/09c7cce2e59e6b3b1807520bcb1980c561f15d1e"},{"url":"https://git.kernel.org/stable/c/89e90b16aadd6e66bd0323bc8dfc76a62e756b57"},{"url":"https://git.kernel.org/stable/c/9414ca3b99e5a7f1f3bf51c2a01b383e1b355dd0"}],"title":"tracing: Fix hist trigger timestamps for buffered events","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-99140","datePublished":"2026-10-28T10:34:51.421Z","dateReserved":"2026-09-25T10:25:14.395Z","dateUpdated":"2026-10-30T12:42:12.896Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-28 11:17:33","lastModifiedDate":"2026-10-30 13:21:48","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"99140","Ordinal":"1","Title":"tracing: Fix hist trigger timestamps for buffered events","CVE":"CVE-2026-99140","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"99140","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix hist trigger timestamps for buffered events\n\nSyzkaller triggered a WARN_ON_ONCE(!nest) warning:\n\n  WARNING: kernel/trace/ring_buffer.c:821 at ring_buffer_event_time_stamp\n  Call trace:\n    ring_buffer_event_time_stamp\n    hist_field_timestamp\n    hist_fn_call\n    event_hist_trigger\n    event_triggers_call\n    __event_trigger_test_discard\n    trace_event_buffer_commit\n    do_trace_event_raw_event_sched_switch\n    trace_event_raw_event_sched_switch\n\nThe warning is probabilistically reproducible and is related to syzkaller\nexecuting the following commands:\n\n  echo 'prev_pid == 999999' > events/sched/sched_switch/filter\n  echo 'hist:keys=common_timestamp' > events/sched/sched_switch/trigger\n\nThe specific triggering process is as follows:\n\nCPU 0                                           CPU 1\n(context switching)                             (echo 'hist:keys=common_timestamp' > \\\n                                                        events/sched/sched_switch/trigger)\ndo_trace_event_raw_event_##call\n  trace_event_buffer_lock_reserve\n    if (!tr->no_filter_buffering_ref &&\n        trace_file->flags & EVENT_FILE_FL_FILTERED)\n        return entry;  // return directly\n                                                event_hist_trigger_parse\n                                                  hist_register_trigger\n                                                    tracing_set_filter_buffering(file->tr, true);\n                                                      tr->no_filter_buffering_ref++;\n    __trace_buffer_lock_reserve\n      rb_start_commit\n        local_inc(&cpu_buffer->committing);  // skipped and not executed\n  trace_event_buffer_commit\n    __event_trigger_test_discard\n      event_triggers_call\n        event_hist_trigger\n          hist_fn_call\n            hist_field_timestamp\n              ring_buffer_event_time_stamp\n                nest = local_read(&cpu_buffer->committing);\n                WARN_ON_ONCE(!nest)  // trigger warning\n\nThe root cause is that when an event file has a filter attached and the\nhist trigger has not yet been attached, trace_event_buffer_lock_reserve()\nwrites the event into the per-CPU trace_buffered_event temp buffer instead\nof reserving it in the ring buffer, so cpu_buffer->committing is not\nincremented. When the event is later processed at commit time by a hist\ntrigger, hist_field_timestamp() -> ring_buffer_event_time_stamp() sees a\nzero committing count, triggering WARN_ON_ONCE(!nest).\n\ntracing_event_time_stamp() was added by commit d8279bfc5e959 (\"tracing:\nAdd tracing_event_time_stamp() API\") for exactly this case: if the event\nis the per-CPU trace_buffered_event, it returns the current ring buffer\ntimestamp. But it never gained a caller. Use it in hist_field_timestamp(),\nso that a hist trigger that races onto a buffered event records the\ncurrent time, which is only marginally later than when the event was\nrecorded, instead of warning and recording a bogus timestamp.","Type":"Description","Title":"tracing: Fix hist trigger timestamps for buffered events"}]}}}