{"id":"CVE-2026-99163","title":"tracing/histograms: Reject non-stacktrace fields for synthetic stacktrace fields","summary":"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)…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 00cf3d672a9dd409418647e9f98784c339c3ff63 < 1f36e4ddd05d540f363dbaa4c23042549f15b3ef","Linux >= 00cf3d672a9dd409418647e9f98784c339c3ff63 < deb336ae7c7b341591a6862cf6fcfeca97c77dfd","Linux >= 00cf3d672a9dd409418647e9f98784c339c3ff63 < a244c241593b5b38a08f0df2cb43c26574efbdcb","Linux b9453380c1c542fd095a4dbe9251eeba4022bbce","Linux 5f52389bdd9eafb63b3a2f804e02aeb17b6a5f55","Linux f3baa42afeea0d5f04ad31525e861199d02210cc","Linux >= 5.10.237 < 5.11","Linux >= 5.15.124 < 5.16","Linux >= 6.1.43 < 6.2","Linux 6.3"],"published":"2026-10-28","updated":"2026-10-28","sourceUpdated":"2026-10-28T10:35:15.577Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99163","references":[{"url":"https://git.kernel.org/stable/c/1f36e4ddd05d540f363dbaa4c23042549f15b3ef"},{"url":"https://git.kernel.org/stable/c/deb336ae7c7b341591a6862cf6fcfeca97c77dfd"},{"url":"https://git.kernel.org/stable/c/a244c241593b5b38a08f0df2cb43c26574efbdcb"}],"tags":["cve.org"],"ingestedAt":"2026-10-28T11:09:40.395Z","slug":"CVE-2026-99163","body":"## Overview\n\nIn 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().\n\n## Affected\n\n- `Linux >= 00cf3d672a9dd409418647e9f98784c339c3ff63 < 1f36e4ddd05d540f363dbaa4c23042549f15b3ef`\n- `Linux >= 00cf3d672a9dd409418647e9f98784c339c3ff63 < deb336ae7c7b341591a6862cf6fcfeca97c77dfd`\n- `Linux >= 00cf3d672a9dd409418647e9f98784c339c3ff63 < a244c241593b5b38a08f0df2cb43c26574efbdcb`\n- `Linux b9453380c1c542fd095a4dbe9251eeba4022bbce`\n- `Linux 5f52389bdd9eafb63b3a2f804e02aeb17b6a5f55`\n- `Linux f3baa42afeea0d5f04ad31525e861199d02210cc`\n- `Linux >= 5.10.237 < 5.11`\n- `Linux >= 5.15.124 < 5.16`\n- `Linux >= 6.1.43 < 6.2`\n- `Linux 6.3`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}