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qemu — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2021-3507

A heap buffer overflow was found in the floppy disk emulator of QEMU up to 6.0.0 (including). It could occur in fdctrl_transfer_handler() in hw/block/fdc.c while processing DMA read data transfers from the floppy drive to the guest system. A privileged guest user could use this flaw to crash the QEMU process on the host resulting in DoS scenario, or potential information leakage from the host memory.

Products
qemu
Affected versions
Not specified
Fixed versions
1:7.1+dfsg-1
CVEs
CVE-2021-3507
Confirmed fixed CVEs
Not specified
Updated in this feed
1 Nov 2026, 00:59 UTC · Revision 1

Source evidence

DEBIAN-CVE-2021-3507

core-osv · Original source

Published 6 May 2021, 16:15 UTC

A heap buffer overflow was found in the floppy disk emulator of QEMU up to 6.0.0 (including). It could occur in fdctrl_transfer_handler() in hw/block/fdc.c while processing DMA read data transfers from the floppy drive to the guest system. A privileged guest user could use this flaw to crash the QEMU process on the host resulting in DoS scenario, or potential information leakage from the host memory.

osv:DEBIAN-CVE-2021-3507

qemu

Fixed versions: 1:7.1+dfsg-1

qemu

Fixed versions: 1:7.1+dfsg-1

qemu

Fixed versions: 1:7.1+dfsg-1

Complete source record
{
  "id": "cbfae5501281a611fa0748a941d31f1e0b2aba24e45711e005fa128c08a1fca9",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2021-3507",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2021-3507",
    "summary": "A heap buffer overflow was found in the floppy disk emulator of QEMU up to 6.0.0 (including). It could occur in fdctrl_transfer_handler() in hw/block/fdc.c while processing DMA read data transfers from the floppy drive to the guest system. A privileged guest user could use this flaw to crash the QEMU process on the host resulting in DoS scenario, or potential information leakage from the host memory.",
    "evidence": "osv:DEBIAN-CVE-2021-3507",
    "products": [
      {
        "name": {
          "value": "qemu",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1:7.1+dfsg-1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "qemu",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1:7.1+dfsg-1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "qemu",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1:7.1+dfsg-1",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "DEBIAN-CVE-2021-3507",
      "aliases": [
        "DEBIAN-CVE-2021-3507"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1:7.1+dfsg-1"
                }
              ]
            }
          ],
          "package": {
            "name": "qemu",
            "purl": "pkg:deb/debian/qemu?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-3507.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1:7.1+dfsg-1"
                }
              ]
            }
          ],
          "package": {
            "name": "qemu",
            "purl": "pkg:deb/debian/qemu?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-3507.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1:7.1+dfsg-1"
                }
              ]
            }
          ],
          "package": {
            "name": "qemu",
            "purl": "pkg:deb/debian/qemu?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-3507.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-23T18:04:00.078692226Z",
      "provider": "osv",
      "upstream": [
        "CVE-2021-3507"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2021-3507"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2021-3507",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 422898,
  "published_at": "2021-05-06T16:15:07.547+00:00"
}