{"api_version":"1","generated_at":"2026-11-01T09:41:16+00:00","cve":"CVE-2026-99163","urls":{"html":"https://cve.report/CVE-2026-99163","api":"https://cve.report/api/cve/CVE-2026-99163.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-99163","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-99163"},"summary":{"title":"tracing/histograms: Reject non-stacktrace fields for synthetic stacktrace fields","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing/histograms: Reject non-stacktrace fields for synthetic stacktrace fields\n\nIn check_synth_field(), when a synthetic event field is a stacktrace\n(field->is_stack) and the histogram field is not a \"long[\" stacktrace\narray, validation falls through to the generic size and signedness\ncomparison.\n\nBecause parse_synth_field() sets a stacktrace field's type to\n\"__data_loc unsigned long[]\", its size is sizeof(u64) and\nsynth_field_signed() marks it as signed.  Consequently, any 8-byte\nsigned scalar histogram field passes the fallback check, and its scalar\nvalue is subsequently dereferenced as a kernel stacktrace pointer in\nget_field_size() and trace_stack().\n\nFurthermore, checking strstr(hist_field->type, \"long[\") is insufficient\nbecause tracepoint fields defined with __bitmask() or __rel_bitmask()\nalso have type \"__data_loc unsigned long[]\" or \"__rel_loc unsigned\nlong[]\", whilst create_hist_field() treats them as 4-byte scalar values\nwithout HIST_FIELD_FL_STACKTRACE.\n\nPropagate HIST_FIELD_FL_STACKTRACE to variable references and field\nvariables (whilst excluding variable aliases from per-element\nstacktrace capture), and reject any mismatch between\nHIST_FIELD_FL_STACKTRACE and field->is_stack in check_synth_field().","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-28 11:17:36","updated_at":"2026-10-31 13:17:58"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/648687f2b448d8527cd7b112fe5d4bd0fec85a87","name":"https://git.kernel.org/stable/c/648687f2b448d8527cd7b112fe5d4bd0fec85a87","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/deb336ae7c7b341591a6862cf6fcfeca97c77dfd","name":"https://git.kernel.org/stable/c/deb336ae7c7b341591a6862cf6fcfeca97c77dfd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/eba0a6365a0f38f7598a02fc7f9ee341c7efe7f5","name":"https://git.kernel.org/stable/c/eba0a6365a0f38f7598a02fc7f9ee341c7efe7f5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a244c241593b5b38a08f0df2cb43c26574efbdcb","name":"https://git.kernel.org/stable/c/a244c241593b5b38a08f0df2cb43c26574efbdcb","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/6c4e4946febb585d2fc93a02a0cd12cec715bb32","name":"https://git.kernel.org/stable/c/6c4e4946febb585d2fc93a02a0cd12cec715bb32","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/326c45c9e201e3ff4c9e9e0e14c2c91364d6c8be","name":"https://git.kernel.org/stable/c/326c45c9e201e3ff4c9e9e0e14c2c91364d6c8be","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1f36e4ddd05d540f363dbaa4c23042549f15b3ef","name":"https://git.kernel.org/stable/c/1f36e4ddd05d540f363dbaa4c23042549f15b3ef","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7e0d05a6234a984ac23b8a563fb7f66f2572b668","name":"https://git.kernel.org/stable/c/7e0d05a6234a984ac23b8a563fb7f66f2572b668","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-99163","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99163","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b9453380c1c542fd095a4dbe9251eeba4022bbce eba0a6365a0f38f7598a02fc7f9ee341c7efe7f5 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5f52389bdd9eafb63b3a2f804e02aeb17b6a5f55 326c45c9e201e3ff4c9e9e0e14c2c91364d6c8be git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f3baa42afeea0d5f04ad31525e861199d02210cc 6c4e4946febb585d2fc93a02a0cd12cec715bb32 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 00cf3d672a9dd409418647e9f98784c339c3ff63 7e0d05a6234a984ac23b8a563fb7f66f2572b668 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.3","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.3 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.273 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.224 5.15.* 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 6.18.59 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":"99163","cve":"CVE-2026-99163","epss":"0.001830000","percentile":"0.079290000","score_date":"2026-10-31","updated_at":"2026-11-01 00:01:49"},"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":"eba0a6365a0f38f7598a02fc7f9ee341c7efe7f5","status":"affected","version":"b9453380c1c542fd095a4dbe9251eeba4022bbce","versionType":"git"},{"lessThan":"326c45c9e201e3ff4c9e9e0e14c2c91364d6c8be","status":"affected","version":"5f52389bdd9eafb63b3a2f804e02aeb17b6a5f55","versionType":"git"},{"lessThan":"6c4e4946febb585d2fc93a02a0cd12cec715bb32","status":"affected","version":"f3baa42afeea0d5f04ad31525e861199d02210cc","versionType":"git"},{"lessThan":"7e0d05a6234a984ac23b8a563fb7f66f2572b668","status":"affected","version":"00cf3d672a9dd409418647e9f98784c339c3ff63","versionType":"git"},{"lessThan":"648687f2b448d8527cd7b112fe5d4bd0fec85a87","status":"affected","version":"00cf3d672a9dd409418647e9f98784c339c3ff63","versionType":"git"},{"lessThan":"1f36e4ddd05d540f363dbaa4c23042549f15b3ef","status":"affected","version":"00cf3d672a9dd409418647e9f98784c339c3ff63","versionType":"git"},{"lessThan":"deb336ae7c7b341591a6862cf6fcfeca97c77dfd","status":"affected","version":"00cf3d672a9dd409418647e9f98784c339c3ff63","versionType":"git"},{"lessThan":"a244c241593b5b38a08f0df2cb43c26574efbdcb","status":"affected","version":"00cf3d672a9dd409418647e9f98784c339c3ff63","versionType":"git"},{"lessThan":"5.10.273","status":"affected","version":"5.10.237","versionType":"semver"},{"lessThan":"5.15.224","status":"affected","version":"5.15.124","versionType":"semver"},{"lessThan":"6.1.191","status":"affected","version":"6.1.43","versionType":"semver"}]},{"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":"6.3"},{"lessThan":"6.3","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.273","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":"5.10.273","versionStartIncluding":"5.10.237","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.224","versionStartIncluding":"5.15.124","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.191","versionStartIncluding":"6.1.43","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.161","versionStartIncluding":"6.3","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.115","versionStartIncluding":"6.3","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.59","versionStartIncluding":"6.3","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.13","versionStartIncluding":"6.3","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"6.3","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing/histograms: Reject non-stacktrace fields for synthetic stacktrace fields\n\nIn check_synth_field(), when a synthetic event field is a stacktrace\n(field->is_stack) and the histogram field is not a \"long[\" stacktrace\narray, validation falls through to the generic size and signedness\ncomparison.\n\nBecause parse_synth_field() sets a stacktrace field's type to\n\"__data_loc unsigned long[]\", its size is sizeof(u64) and\nsynth_field_signed() marks it as signed.  Consequently, any 8-byte\nsigned scalar histogram field passes the fallback check, and its scalar\nvalue is subsequently dereferenced as a kernel stacktrace pointer in\nget_field_size() and trace_stack().\n\nFurthermore, checking strstr(hist_field->type, \"long[\") is insufficient\nbecause tracepoint fields defined with __bitmask() or __rel_bitmask()\nalso have type \"__data_loc unsigned long[]\" or \"__rel_loc unsigned\nlong[]\", whilst create_hist_field() treats them as 4-byte scalar values\nwithout HIST_FIELD_FL_STACKTRACE.\n\nPropagate HIST_FIELD_FL_STACKTRACE to variable references and field\nvariables (whilst excluding variable aliases from per-element\nstacktrace capture), and reject any mismatch between\nHIST_FIELD_FL_STACKTRACE and field->is_stack in check_synth_field()."}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - Local writes to tracefs synthetic_events and events/.../trigger supply the bad field/action; event_trigger_write() → event_hist_trigger_parse() → create_actions() → the patched check_synth_field(). No network or physical input reaches it.\nAC:L - The attacker can deterministically create the stack field, map an 8-byte signed scalar or expression to it, enable the synthetic event, and issue their own triggering syscall; no race or uncontrollable state is required.\nPR:L - Although these files are mode 0640, tracefs_parse_param() accepts uid= and tracefs_apply_options() propagates that owner to synthetic_events and eventfs trigger files, allowing a delegated non-root tracing account to write both; user namespaces alone cannot mount tracefs.\nUI:N - The attacker performs every required tracefs write and triggers the configured histogram through their own syscall or selected tracepoint, without another user's action.\nS:U - The invalid pointer dereference and ring-buffer overwrite occur entirely within the host kernel's tracing subsystem and do not cross a VM, IOMMU, or separate security authority.\nC:H - An 8-byte signed histogram expression can hold a chosen address; get_field_size() dereferences it and trace_stack() copies up to 16 machine words into a synthetic-event record readable from the trace buffer, permitting repeatable kernel-memory disclosure.\nI:H - get_field_size() sizes the record from the pointer's first word, while trace_stack() independently scans up to 16 nonzero words before memcpy(); a mismatched count therefore writes past the reserved ring-buffer record.\nA:H - Mapping raw_syscalls:sys_enter.id directly to the stack field makes get_field_size() dereference a small invalid address on the attacker's next syscall, producing a deterministic, repeatable kernel oops."}]}],"providerMetadata":{"dateUpdated":"2026-10-31T12:44:20.055Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/eba0a6365a0f38f7598a02fc7f9ee341c7efe7f5"},{"url":"https://git.kernel.org/stable/c/326c45c9e201e3ff4c9e9e0e14c2c91364d6c8be"},{"url":"https://git.kernel.org/stable/c/6c4e4946febb585d2fc93a02a0cd12cec715bb32"},{"url":"https://git.kernel.org/stable/c/7e0d05a6234a984ac23b8a563fb7f66f2572b668"},{"url":"https://git.kernel.org/stable/c/648687f2b448d8527cd7b112fe5d4bd0fec85a87"},{"url":"https://git.kernel.org/stable/c/1f36e4ddd05d540f363dbaa4c23042549f15b3ef"},{"url":"https://git.kernel.org/stable/c/deb336ae7c7b341591a6862cf6fcfeca97c77dfd"},{"url":"https://git.kernel.org/stable/c/a244c241593b5b38a08f0df2cb43c26574efbdcb"}],"title":"tracing/histograms: Reject non-stacktrace fields for synthetic stacktrace fields","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-99163","datePublished":"2026-10-28T10:35:15.577Z","dateReserved":"2026-09-25T10:25:14.398Z","dateUpdated":"2026-10-31T12:44:20.055Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-28 11:17:36","lastModifiedDate":"2026-10-31 13:17:58","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"99163","Ordinal":"1","Title":"tracing/histograms: Reject non-stacktrace fields for synthetic s","CVE":"CVE-2026-99163","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"99163","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing/histograms: Reject non-stacktrace fields for synthetic stacktrace fields\n\nIn check_synth_field(), when a synthetic event field is a stacktrace\n(field->is_stack) and the histogram field is not a \"long[\" stacktrace\narray, validation falls through to the generic size and signedness\ncomparison.\n\nBecause parse_synth_field() sets a stacktrace field's type to\n\"__data_loc unsigned long[]\", its size is sizeof(u64) and\nsynth_field_signed() marks it as signed.  Consequently, any 8-byte\nsigned scalar histogram field passes the fallback check, and its scalar\nvalue is subsequently dereferenced as a kernel stacktrace pointer in\nget_field_size() and trace_stack().\n\nFurthermore, checking strstr(hist_field->type, \"long[\") is insufficient\nbecause tracepoint fields defined with __bitmask() or __rel_bitmask()\nalso have type \"__data_loc unsigned long[]\" or \"__rel_loc unsigned\nlong[]\", whilst create_hist_field() treats them as 4-byte scalar values\nwithout HIST_FIELD_FL_STACKTRACE.\n\nPropagate HIST_FIELD_FL_STACKTRACE to variable references and field\nvariables (whilst excluding variable aliases from per-element\nstacktrace capture), and reject any mismatch between\nHIST_FIELD_FL_STACKTRACE and field->is_stack in check_synth_field().","Type":"Description","Title":"tracing/histograms: Reject non-stacktrace fields for synthetic s"}]}}}