Security advisory

{
  "id": "f7aa07b0b23738fcc87624ce45278699b1ae051d3c95d35616c6a7d6e838d9a1",
  "url": "https://osv.dev/vulnerability/CVE-2021-20196",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-20196",
    "summary": "A NULL pointer dereference flaw was found in the floppy disk emulator of QEMU. This issue occurs while processing read/write ioport commands if the selected floppy drive is not initialized with a block device. This flaw allows a privileged guest user to crash the QEMU process on the host, resulting in a denial of service. The highest threat from this vulnerability is to system availability.",
    "evidence": "osv:CVE-2021-20196",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2021-20196",
      "aliases": [
        "CVE-2021-20196"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/qemu/qemu",
              "type": "GIT",
              "events": [
                {
                  "introduced": "553032db17440f8de011390e5a1cfddd13751b0b"
                },
                {
                  "last_affected": "553032db17440f8de011390e5a1cfddd13751b0b"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:qemu:qemu:5.2.0:-:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "5.2.0-NA"
                      },
                      {
                        "last_affected": "5.2.0-NA"
                      }
                    ],
                    "source": "CPE_STRING"
                  }
                ]
              }
            }
          ],
          "versions": [
            "5.2.0-NA",
            "v5.2.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-20196.json"
          }
        },
        {
          "ranges": [
            {
              "repo": "https://gitlab.com/qemu-project/qemu",
              "type": "GIT",
              "events": [
                {
                  "introduced": "553032db17440f8de011390e5a1cfddd13751b0b"
                },
                {
                  "last_affected": "553032db17440f8de011390e5a1cfddd13751b0b"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:qemu:qemu:5.2.0:-:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "5.2.0-NA"
                      },
                      {
                        "last_affected": "5.2.0-NA"
                      }
                    ],
                    "source": "CPE_STRING"
                  }
                ]
              }
            }
          ],
          "versions": [
            "5.2.0-NA",
            "v5.2.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-20196.json"
          }
        }
      ],
      "modified": "2026-10-24T10:30:48.537781957Z",
      "provider": "osv",
      "references": [
        "https://lists.debian.org/debian-lts-announce/2022/04/msg00002.html",
        "https://lists.debian.org/debian-lts-announce/2022/09/msg00008.html",
        "https://security.netapp.com/advisory/ntap-20210708-0004/",
        "https://bugs.launchpad.net/qemu/+bug/1912780",
        "https://www.openwall.com/lists/oss-security/2021/01/28/1"
      ],
      "provider_metadata": {
        "unresolved_ranges": [
          {
            "cpes": [
              "cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*",
              "cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*"
            ],
            "vendor_product": "debian:debian_linux",
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "9.0"
                  },
                  {
                    "last_affected": "9.0"
                  },
                  {
                    "introduced": "10.0"
                  },
                  {
                    "last_affected": "10.0"
                  }
                ],
                "source": "CPE_STRING"
              }
            ]
          }
        ]
      }
    },
    "related_cves": [
      {
        "value": "CVE-2021-20196",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 436793,
  "published_at": "2021-05-26T22:15:07.907+00:00"
}