FreeBSD-EN-26:20.microcode Errata Notice

{
  "id": "41674c7279516d66023ac4fa1f79376fbd7f1f2c5afe44003df7c8a315071515",
  "url": "https://www.freebsd.org/security/advisories/FreeBSD-EN-26:20.microcode.asc",
  "method": "llm",
  "payload": {
    "kind": "patch",
    "title": "FreeBSD-EN-26:20.microcode Errata Notice",
    "summary": "A bounds-check bug prevented early Intel microcode loading for some CPUs whose matching signatures appeared only in extended signature tables. FreeBSD corrected the issue in the listed branches; late loading was not affected.",
    "evidence": "The kernel's early-loading matcher, ucode_intel_match() in sys/x86/x86/ucode.c, contained an inverted bounds check that caused the extended signature table to always be treated as absent.",
    "products": [
      {
        "name": {
          "value": "FreeBSD",
          "evidence": "All supported versions of FreeBSD."
        },
        "prerequisites": [
          {
            "value": "Intel CPUs",
            "evidence": "On affected Intel CPUs, early loading applies no microcode update even when a suitable update is present in the loaded file."
          },
          {
            "value": "a CPU whose matching signature+platform pair appears only in an image's extended signature table",
            "evidence": "Consequently, a CPU whose matching signature+platform pair appears only in an image's extended signature table was never matched during early loading, and its microcode update was not applied."
          }
        ],
        "fixed_versions": [
          {
            "value": "15.1-RELEASE-p3",
            "evidence": "2026-08-25 16:01:16 UTC (releng/15.1, 15.1-RELEASE-p3)"
          },
          {
            "value": "15.0-RELEASE-p13",
            "evidence": "2026-08-25 16:00:56 UTC (releng/15.0, 15.0-RELEASE-p13)"
          },
          {
            "value": "14.4-RELEASE-p9",
            "evidence": "2026-08-25 16:00:22 UTC (releng/14.4, 14.4-RELEASE-p9)"
          }
        ],
        "affected_versions": [
          {
            "value": "All supported versions of FreeBSD",
            "evidence": "Affects: All supported versions of FreeBSD."
          }
        ]
      }
    ],
    "severity": "unknown",
    "fixed_cves": [],
    "related_cves": [],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "official-freebsd-security",
  "document_id": 23604,
  "published_at": "2026-08-25T00:00:00+00:00"
}