{ "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///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" } } } }