{"cve":"CVE-2021-20196","nvd":{"published":"2021-05-26T22:15:07.907","modified":"2026-06-17T03:33:27.217","status":"Modified","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H","score":6.5},"cwes":["CWE-476"],"references":["https://bugs.launchpad.net/qemu/+bug/1912780","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://www.openwall.com/lists/oss-security/2021/01/28/1"],"products":["debian:debian_linux","qemu:qemu"],"source":"nvd","synced_at":"2026-10-19T21:18:09.669877188+00:00"},"epss":{"cve":"CVE-2021-20196","score":0.00479,"percentile":0.41365,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}