{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99235","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-25T10:25:14.402Z","datePublished":"2026-11-02T16:06:41.510Z","dateUpdated":"2026-11-03T19:13:03.627Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-11-03T19:13:03.627Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Save the event file instead of the compatible histogram\n\ncreate_field_var_hist() creates a histogram on the matched event to\nsupply a field variable, and records it on the target so it can be torn\ndown later:\n\n\thist_data = find_compatible_hist(target_hist_data, file);\n\t...\n\t/* Save the compatible histogram information */\n\tvar_hist->hist_data = hist_data;\n\nhist_data is not the histogram it creates. It is one that was already\nthere, whose keys the new one copies. The saved pointer has a single\nuser, unregister_field_var_hists(), which runs when the target is\nremoved:\n\n\tfile = hist_data->field_var_hists[i]->hist_data->event_file;\n\nfind_compatible_hist() matches on keys alone, so it can pick one with no\nvariables of its own. check_var_refs() then returns false and the user\ncan remove it while the target still points at it:\n\n BUG: KASAN: slab-use-after-free in event_hist_trigger_free+0x2b2/0x320\n Read of size 8 at addr ffff8880093b90e0 by task init/1\n\n Freed by task 1:\n  kfree+0x154/0x420\n  event_hist_trigger_free+0x1d5/0x320\n  event_hist_trigger_parse+0x35f3/0x69e0\n  trigger_process_regex+0x1a6/0x250\n\nSave the event file instead. It is all the dereference ever wanted, and\nit does not go away when the user removes a trigger."}],"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 attacker-controlled hist text is written locally to events/<sys>/<event>/trigger: event_trigger_write() -> trigger_process_regex() -> event_hist_trigger_parse() -> create_actions()/onmatch_create() -> trace_action_create_field_var() -> create_field_var_hist(). No remote protocol carries the keys or onmatch() field names that make find_compatible_hist() save the dangling pointer.\nAC:L - The attacker writes a keys-only hist on event A, an onmatch().trace() hist on event B so create_field_var_hist() stores A's hist_data, then '!hist' on A and on B. find_compatible_hist() matches keys only, so check_var_refs() lets A be removed; event_mutex serializes every write, with no race or victim state.\nPR:L - create_field_var_hist() is reached only after writes to a TRACE_MODE_WRITE (0640) trigger file and to synthetic_events; event_trigger_regex_open() and the synth file enforce LOCKDOWN_TRACEFS and DAC, not capable(). tracefs_parse_param() uid= is applied by tracefs_apply_options() onto those inodes, so a delegated non-root tracing owner can run the onmatch() sequence; userns cannot mount tracefs.\nUI:N - The attacker performs the compatible-hist write, the onmatch().trace() write that calls create_field_var_hist(), and both '!hist' removals themselves. No other user must mount media, open a file, or enable tracing.\nS:U - The slab use-after-free of the compatible hist_trigger_data is in the host kernel's tracing heap (event_hist_trigger_free()/unregister_field_var_hists()). It does not cross a VM, IOMMU, or sandbox boundary.\nC:H - unregister_field_var_hists() reads field_var_hists[i]->hist_data->event_file from the hist_trigger_data that event_hist_trigger_free() already kfree'd (KASAN 8-byte read). After reclaiming that slab, the attacker controls the pointer then walked as a trace_event_file, a use-after-free read primitive.\nI:H - That attacker-controlled event_file is passed to event_hist_trigger_parse(\"!hist\"), which list_del_rcu()s file->triggers and runs cmd_ops->free on objects taken from the sprayed hist_trigger_data, a heap write and control-flow primitive.\nA:H - The commit reproduces a KASAN slab-use-after-free in event_hist_trigger_free() when the target hist is removed after the compatible one. Without KASAN, the stale hist_data->event_file dereference oopses or panics the kernel."}]}],"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"],"versions":[{"version":"02205a6752f223779a1b0e9e8ffacbea6e717851","lessThan":"a6165126b1a1b26342b55be6eb6ee23af8756aba","status":"affected","versionType":"git"},{"version":"02205a6752f223779a1b0e9e8ffacbea6e717851","lessThan":"173914501b97236d7ea7dc2af7f30feddd4e1436","status":"affected","versionType":"git"},{"version":"02205a6752f223779a1b0e9e8ffacbea6e717851","lessThan":"ac815a379644b2ad5008a009a3516ada31b5dd82","status":"affected","versionType":"git"},{"version":"02205a6752f223779a1b0e9e8ffacbea6e717851","lessThan":"8b307d64a60548e4a74cb746f74d7ed4bd49965e","status":"affected","versionType":"git"},{"version":"02205a6752f223779a1b0e9e8ffacbea6e717851","lessThan":"7a111ba0d1b74c99bc8f096565dc71945f694254","status":"affected","versionType":"git"},{"version":"02205a6752f223779a1b0e9e8ffacbea6e717851","lessThan":"3609ada3c12cecfb0ae5ee82ef4f86c5f18a2dea","status":"affected","versionType":"git"},{"version":"02205a6752f223779a1b0e9e8ffacbea6e717851","lessThan":"9631dbccd3c649b567a5aafffea6b00634183997","status":"affected","versionType":"git"},{"version":"02205a6752f223779a1b0e9e8ffacbea6e717851","lessThan":"7cafc82e6153f05a221be678cd649d02e06ba909","status":"affected","versionType":"git"},{"version":"02205a6752f223779a1b0e9e8ffacbea6e717851","lessThan":"d5c42664fc094899af9aae5300b27fe8fdb658ef","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"],"versions":[{"version":"4.17","status":"affected"},{"version":"0","lessThan":"4.17","status":"unaffected","versionType":"semver"},{"version":"5.10.273","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.224","lessThanOrEqual":"5.15.*","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":"5.10.273"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"5.15.224"},{"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/a6165126b1a1b26342b55be6eb6ee23af8756aba"},{"url":"https://git.kernel.org/stable/c/173914501b97236d7ea7dc2af7f30feddd4e1436"},{"url":"https://git.kernel.org/stable/c/ac815a379644b2ad5008a009a3516ada31b5dd82"},{"url":"https://git.kernel.org/stable/c/8b307d64a60548e4a74cb746f74d7ed4bd49965e"},{"url":"https://git.kernel.org/stable/c/7a111ba0d1b74c99bc8f096565dc71945f694254"},{"url":"https://git.kernel.org/stable/c/3609ada3c12cecfb0ae5ee82ef4f86c5f18a2dea"},{"url":"https://git.kernel.org/stable/c/9631dbccd3c649b567a5aafffea6b00634183997"},{"url":"https://git.kernel.org/stable/c/7cafc82e6153f05a221be678cd649d02e06ba909"},{"url":"https://git.kernel.org/stable/c/d5c42664fc094899af9aae5300b27fe8fdb658ef"}],"title":"tracing: Save the event file instead of the compatible histogram","x_generator":{"engine":"bippy-1.2.0"}}}}