FKIE_CVE-2026-102916

Vulnerability from fkie_nvd - Published: 2026-10-09 15:17 - Updated: 2026-10-09 22:16
Severity
6.8 (Medium) - CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:P/AU:Y/R:A/V:C
Summary
A reachable assertion in the illumos bhyve instruction emulator allows a guest to panic the host. When emulating a REP-prefixed MOVS or STOS instruction that accesses guest MMIO, vie_emulate_movs() and vie_emulate_stos() in usr/src/uts/intel/io/vmm/vmm_instruction_emul.c do not clear the VIES_REPEAT status flag on the final iteration. For MMIO regions emulated in the kernel (the local APIC, I/O APIC and HPET), the stale flag causes a VERIFY assertion in vie_advance_pc() to fail, and the host panics. A privileged user within a guest VM can issue a REP MOVS or REP STOS instruction against the local APIC page to cause a denial of service of the host and every other guest running on it. The flaw has existed since 2020 (illumos-gate commit e0c0d44e), and affects any illumos distribution prior to illumos-gate commit 696ecf8d.
References
0ca53633-f0b5-4853-ba72-e0a2e62000d0https://github.com/illumos/illumos-gate/commit/696ecf8debceed9dc33937d8c8e111e4aeebfdae
0ca53633-f0b5-4853-ba72-e0a2e62000d0https://illumos.org/issues/18491
0ca53633-f0b5-4853-ba72-e0a2e62000d0https://illumos.topicbox.com/groups/developer/T697a32b688807e56/cve-2026-102916-18491-bhyve-rep-prefix-instr-emulation-fumbles-flags
af854a3a-2127-422b-91ae-364da2661108http://www.openwall.com/lists/oss-security/2026/10/09/19
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://illumos.org",
          "defaultStatus": "affected",
          "modules": [
            "kernel",
            "bhyve",
            "vmm"
          ],
          "packageName": "system/bhyve",
          "platforms": [
            "x86"
          ],
          "product": "illumos-gate",
          "programFiles": [
            "usr/src/uts/intel/io/vmm/vmm_instruction_emul.c"
          ],
          "repo": "https://github.com/illumos/illumos-gate",
          "vendor": "illumos",
          "versions": [
            {
              "changes": [
                {
                  "at": "696ecf8debceed9dc33937d8c8e111e4aeebfdae",
                  "status": "unaffected"
                }
              ],
              "lessThan": "696ecf8debceed9dc33937d8c8e111e4aeebfdae",
              "status": "affected",
              "version": "e0c0d44e917080841514d0dd031a696c74e8c435",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "OmniOS",
          "vendor": "OmniOS",
          "versions": [
            {
              "lessThan": "r151054",
              "status": "affected",
              "version": "any",
              "versionType": "custom"
            },
            {
              "changes": [
                {
                  "at": "r151058w",
                  "status": "unaffected"
                }
              ],
              "lessThan": "r151058w",
              "status": "affected",
              "version": "r151058",
              "versionType": "custom"
            },
            {
              "changes": [
                {
                  "at": "r151056aw",
                  "status": "unaffected"
                }
              ],
              "lessThan": "r151056aw",
              "status": "affected",
              "version": "r151056",
              "versionType": "custom"
            },
            {
              "changes": [
                {
                  "at": "r151054bw",
                  "status": "unaffected"
                }
              ],
              "lessThan": "r151054bw",
              "status": "affected",
              "version": "r151054",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "0ca53633-f0b5-4853-ba72-e0a2e62000d0"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A reachable assertion in the illumos bhyve instruction emulator allows a guest to panic the host. When emulating a REP-prefixed MOVS or STOS instruction that accesses guest MMIO, vie_emulate_movs() and vie_emulate_stos() in usr/src/uts/intel/io/vmm/vmm_instruction_emul.c do not clear the VIES_REPEAT status flag on the final iteration. For MMIO regions emulated in the kernel (the local APIC, I/O APIC and HPET), the stale flag causes a VERIFY assertion in vie_advance_pc() to fail, and the host panics. A privileged user within a guest VM can issue a REP MOVS or REP STOS instruction against the local APIC page to cause a denial of service of the host and every other guest running on it. The flaw has existed since 2020 (illumos-gate commit e0c0d44e), and affects any illumos distribution prior to illumos-gate commit 696ecf8d."
    }
  ],
  "id": "CVE-2026-102916",
  "lastModified": "2026-10-09T22:16:55.220",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "YES",
          "Recovery": "AUTOMATIC",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "LOCAL",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.8,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "PROOF_OF_CONCEPT",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "LOW",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "HIGH",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "CONCENTRATED",
          "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:A/V:C/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "HIGH",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "0ca53633-f0b5-4853-ba72-e0a2e62000d0",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-102916",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-10-09T16:15:23.994154Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-10-09T15:17:06.560",
  "references": [
    {
      "source": "0ca53633-f0b5-4853-ba72-e0a2e62000d0",
      "url": "https://github.com/illumos/illumos-gate/commit/696ecf8debceed9dc33937d8c8e111e4aeebfdae"
    },
    {
      "source": "0ca53633-f0b5-4853-ba72-e0a2e62000d0",
      "url": "https://illumos.org/issues/18491"
    },
    {
      "source": "0ca53633-f0b5-4853-ba72-e0a2e62000d0",
      "url": "https://illumos.topicbox.com/groups/developer/T697a32b688807e56/cve-2026-102916-18491-bhyve-rep-prefix-instr-emulation-fumbles-flags"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "http://www.openwall.com/lists/oss-security/2026/10/09/19"
    }
  ],
  "sourceIdentifier": "0ca53633-f0b5-4853-ba72-e0a2e62000d0",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-617"
        }
      ],
      "source": "0ca53633-f0b5-4853-ba72-e0a2e62000d0",
      "type": "Secondary"
    }
  ]
}



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