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Qemu-kvm: hyperv/syndbg: missing mapped-length guard after cpu_physical_memory_map causes host oob write

Type: advisorySources: OSV

A flaw was found in QEMU. This vulnerability allows a local attacker within a guest virtual machine to write data beyond its allocated memory. This occurs when cpu_physical_memory_map() returns a shorter length than expected, leading to an out-of-bounds write. Successful exploitation could result in unauthorized access to guest memory or corruption of heap-allocated objects, potentially causing information disclosure, data integrity issues, or a denial of service.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-3842
Confirmed fixed CVEs
Not specified
Updated in this feed
2 Nov 2026, 23:50 UTC · Revision 1

Source evidence

Qemu-kvm: hyperv/syndbg: missing mapped-length guard after cpu_physical_memory_map causes host oob write

core-osv · Original source

Published 16 Jul 2026, 00:20 UTC

A flaw was found in QEMU. This vulnerability allows a local attacker within a guest virtual machine to write data beyond its allocated memory. This occurs when cpu_physical_memory_map() returns a shorter length than expected, leading to an out-of-bounds write. Successful exploitation could result in unauthorized access to guest memory or corruption of heap-allocated objects, potentially causing information disclosure, data integrity issues, or a denial of service.

osv:CVE-2026-3842
Complete source record
{
  "id": "9d2e8d31a201b1612983c0a8c84850f63427e8157456f57008688e3bd4bc02b7",
  "url": "https://osv.dev/vulnerability/CVE-2026-3842",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Qemu-kvm: hyperv/syndbg: missing mapped-length guard after cpu_physical_memory_map causes host oob write",
    "summary": "A flaw was found in QEMU. This vulnerability allows a local attacker within a guest virtual machine to write data beyond its allocated memory. This occurs when cpu_physical_memory_map() returns a shorter length than expected, leading to an out-of-bounds write. Successful exploitation could result in unauthorized access to guest memory or corruption of heap-allocated objects, potentially causing information disclosure, data integrity issues, or a denial of service.",
    "evidence": "osv:CVE-2026-3842",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-3842",
      "aliases": [
        "CVE-2026-3842"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://gitlab.com/qemu-project/qemu",
              "type": "GIT",
              "events": [
                {
                  "introduced": "621da7789083b80d6f1ff1c0fb499334007b4f51"
                },
                {
                  "fixed": "98b060da3a4f92b2a994ead5b16a87e783baf77c"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "7.1.0"
                      },
                      {
                        "fixed": "11.0.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v11.0.0-rc4",
            "v11.0.0-rc3",
            "v11.0.0-rc2",
            "v11.0.0-rc1",
            "v11.0.0-rc0",
            "v10.2.0",
            "v10.2.0-rc4",
            "v10.2.0-rc3",
            "v10.2.0-rc2",
            "v10.2.0-rc1",
            "v10.1.0",
            "v10.1.0-rc4",
            "v10.1.0-rc3",
            "v10.1.0-rc2",
            "v10.1.0-rc1",
            "v10.1.0-rc0",
            "v10.0.0",
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            "v10.0.0-rc3",
            "v10.0.0-rc2",
            "v10.0.0-rc1",
            "v10.0.0-rc0",
            "v9.2.0",
            "v9.2.0-rc3",
            "v9.2.0-rc0",
            "v9.2.0-rc2",
            "v9.2.0-rc1",
            "v9.1.0",
            "v9.1.0-rc4",
            "v9.1.0-rc3",
            "v9.1.0-rc2",
            "v9.1.0-rc1",
            "v9.1.0-rc0",
            "v9.0.0",
            "v9.0.0-rc4",
            "v9.0.0-rc3",
            "v9.0.0-rc2",
            "v9.0.0-rc1",
            "v9.0.0-rc0",
            "v8.2.0",
            "v8.2.0-rc4",
            "v8.2.0-rc3",
            "v8.2.0-rc2",
            "v8.2.0-rc1",
            "v8.2.0-rc0",
            "v8.1.0",
            "v8.1.0-rc4",
            "v8.1.0-rc3",
            "v8.1.0-rc2",
            "v8.1.0-rc1",
            "v8.1.0-rc0",
            "v8.0.0",
            "v8.0.0-rc4",
            "v8.0.0-rc3",
            "v8.0.0-rc2",
            "v7.2.0",
            "v8.0.0-rc1",
            "v8.0.0-rc0",
            "v7.2.0-rc4",
            "v7.2.0-rc3",
            "v7.2.0-rc2",
            "v7.2.0-rc1",
            "v7.2.0-rc0",
            "v7.1.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-3842.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:24.391264092Z",
      "provider": "osv",
      "references": [
        "https://access.redhat.com/downloads/content/package-browser/",
        "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-3842.json",
        "https://access.redhat.com/security/cve/CVE-2026-3842",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/3xxx/CVE-2026-3842.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-3842",
        "https://bugzilla.redhat.com/show_bug.cgi?id=2458150",
        "https://gitlab.com/qemu-project/qemu"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-787"
        ],
        "cna_assigner": "fedora",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/3xxx/CVE-2026-3842.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-3842",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 490979,
  "published_at": "2026-07-16T00:20:02.91+00:00"
}