{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99163","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-25T10:25:14.398Z","datePublished":"2026-10-28T10:35:15.577Z","dateUpdated":"2026-10-31T12:44:20.055Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-10-31T12:44:20.055Z"},"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":{"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 - 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."}]}],"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":"b9453380c1c542fd095a4dbe9251eeba4022bbce","lessThan":"eba0a6365a0f38f7598a02fc7f9ee341c7efe7f5","status":"affected","versionType":"git"},{"version":"5f52389bdd9eafb63b3a2f804e02aeb17b6a5f55","lessThan":"326c45c9e201e3ff4c9e9e0e14c2c91364d6c8be","status":"affected","versionType":"git"},{"version":"f3baa42afeea0d5f04ad31525e861199d02210cc","lessThan":"6c4e4946febb585d2fc93a02a0cd12cec715bb32","status":"affected","versionType":"git"},{"version":"00cf3d672a9dd409418647e9f98784c339c3ff63","lessThan":"7e0d05a6234a984ac23b8a563fb7f66f2572b668","status":"affected","versionType":"git"},{"version":"00cf3d672a9dd409418647e9f98784c339c3ff63","lessThan":"648687f2b448d8527cd7b112fe5d4bd0fec85a87","status":"affected","versionType":"git"},{"version":"00cf3d672a9dd409418647e9f98784c339c3ff63","lessThan":"1f36e4ddd05d540f363dbaa4c23042549f15b3ef","status":"affected","versionType":"git"},{"version":"00cf3d672a9dd409418647e9f98784c339c3ff63","lessThan":"deb336ae7c7b341591a6862cf6fcfeca97c77dfd","status":"affected","versionType":"git"},{"version":"00cf3d672a9dd409418647e9f98784c339c3ff63","lessThan":"a244c241593b5b38a08f0df2cb43c26574efbdcb","status":"affected","versionType":"git"},{"version":"5.10.237","lessThan":"5.10.273","status":"affected","versionType":"semver"},{"version":"5.15.124","lessThan":"5.15.224","status":"affected","versionType":"semver"},{"version":"6.1.43","lessThan":"6.1.191","status":"affected","versionType":"semver"}]},{"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":"6.3","status":"affected"},{"version":"0","lessThan":"6.3","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":"6.18.59","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.13","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","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":"5.10.237","versionEndExcluding":"5.10.273"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15.124","versionEndExcluding":"5.15.224"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.43","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.6.161"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.12.115"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.18.59"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"7.2.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"7.3"}]}]}],"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"}}}}