{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99233","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-25T10:25:14.402Z","datePublished":"2026-11-02T16:06:40.643Z","dateUpdated":"2026-11-03T19:13:02.404Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-11-03T19:13:02.404Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing/histograms: Verify event_call identity when updating synth_event refcount\n\nIn event_hist_trigger_parse() and hist_unreg_all(), the histogram\nregistration and unregistration paths look up find_synth_event() using\ntrace_event_name(file->event_call) and adjust se->ref if a match is\nfound.\n\nBecause find_synth_event() only compares the event basename, registering\nor removing a histogram on a non-synthetic trace event whose basename\nmatches a synthetic event erroneously modifies the synthetic event's\nreference count.  If a histogram is registered on the non-synthetic\nevent before the synthetic event is created and removed afterwards,\nse->ref is decremented without a matching increment, allowing the\nsynthetic event to be freed while an active histogram action still holds\na pointer to it.\n\nIntroduce find_synth_event_call() to verify that &se->call matches\nfile->event_call before adjusting se->ref."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The colliding basename is supplied by local writes: event_trigger_write() → trigger_process_regex() → event_hist_trigger_parse()/hist_unreg_all() on events/<system>/<event>/trigger, and synth_events_write() → create_or_delete_synth_event() on synthetic_events. No network protocol carries this input.\nAC:L - The attacker drives a fully ordered sequence: a hist on a non-synth event (no se->ref++), then a same-basename synth event, then an ACTION_TRACE hist that stores data->synth_event and increments se->ref, then the !hist/hist_unreg_all path which decrements se->ref, then synth_event_delete(). event_mutex serializes it; no victim-owned state is required.\nPR:L - event_trigger_open() and synth_events_open() only call security_locked_down(LOCKDOWN_TRACEFS); both files are TRACE_MODE_WRITE (0640) with no capable() check. tracefs_parse_param() accepts uid=/gid= and tracefs_apply_options() applies that owner, so a delegated tracing user can write them; tracefs has no FS_USERNS_MOUNT.\nUI:N - The attacker writes the hist commands, creates and deletes the colliding synth event via synth_events_write(), and can fire the leftover ACTION_TRACE histogram from their own process (any syscall that hits the remaining event). No separate victim action is required.\nS:U - destroy_synth_event() kfree's struct synth_event while action_trace() still holds data->synth_event; that UAF is confined to the host tracing heap and does not cross a VM, IOMMU, or sandbox boundary.\nC:H - Once free_synth_event() has kfree'd the object, action_trace() still reads data->synth_event and trace_synth() follows event->tp and tp->funcs; reclaiming that kmalloc object lets the attacker control those reads, giving a kernel-memory disclosure primitive.\nI:H - trace_synth() calls probe_func taken from the dangling event->tp->funcs, and a later action_data_destroy() does data->synth_event->ref-- on the freed object; spraying the reclaimed synth_event therefore yields a function-pointer hijack and a write primitive.\nA:H - trace_synth() does static_key_enabled(&tp->key) on event->tp from the freed synth_event the first time the leftover histogram fires, which oopses on a poisoned or unmapped pointer; the UAF is repeatable at will."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/trace_events_hist.c","kernel/trace/trace_events_synth.c","kernel/trace/trace_synth.h"],"versions":[{"version":"4b147936fa509650beaf638b331573c23ba4d609","lessThan":"381f543ed35c434d5b707369aa5dcd69ecf440af","status":"affected","versionType":"git"},{"version":"4b147936fa509650beaf638b331573c23ba4d609","lessThan":"4472579bd1c83708b6fe623c870cdf728e947205","status":"affected","versionType":"git"},{"version":"4b147936fa509650beaf638b331573c23ba4d609","lessThan":"23b4106e8b35823acc79e206c7745f55b9cfd78b","status":"affected","versionType":"git"},{"version":"4b147936fa509650beaf638b331573c23ba4d609","lessThan":"06e816bed499fe47f39f12044382cc5d064485fb","status":"affected","versionType":"git"},{"version":"4b147936fa509650beaf638b331573c23ba4d609","lessThan":"5597bb8db6855fcb97a67196d227fea359bcd81c","status":"affected","versionType":"git"},{"version":"4b147936fa509650beaf638b331573c23ba4d609","lessThan":"cf4e31d5da80fae4c9cdbe7af55b7c3ad213f0e4","status":"affected","versionType":"git"},{"version":"4b147936fa509650beaf638b331573c23ba4d609","lessThan":"3403d9bb27ebc3572bd048620746b4414e073bf9","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/trace_events_hist.c","kernel/trace/trace_events_synth.c","kernel/trace/trace_synth.h"],"versions":[{"version":"4.17","status":"affected"},{"version":"0","lessThan":"4.17","status":"unaffected","versionType":"semver"},{"version":"6.1.191","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.161","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.115","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.60","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.14","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3.1","lessThanOrEqual":"7.3.*","status":"unaffected","versionType":"semver"},{"version":"7.4-rc1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"6.6.161"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"6.12.115"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"6.18.60"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"7.2.14"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"7.3.1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"7.4-rc1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/381f543ed35c434d5b707369aa5dcd69ecf440af"},{"url":"https://git.kernel.org/stable/c/4472579bd1c83708b6fe623c870cdf728e947205"},{"url":"https://git.kernel.org/stable/c/23b4106e8b35823acc79e206c7745f55b9cfd78b"},{"url":"https://git.kernel.org/stable/c/06e816bed499fe47f39f12044382cc5d064485fb"},{"url":"https://git.kernel.org/stable/c/5597bb8db6855fcb97a67196d227fea359bcd81c"},{"url":"https://git.kernel.org/stable/c/cf4e31d5da80fae4c9cdbe7af55b7c3ad213f0e4"},{"url":"https://git.kernel.org/stable/c/3403d9bb27ebc3572bd048620746b4414e073bf9"}],"title":"tracing/histograms: Verify event_call identity when updating synth_event refcount","x_generator":{"engine":"bippy-1.2.0"}}}}