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Vulnerability record · CVE-2021-20257 · published 16 March 2022

CVE-2021-20257: Qemu vulnerability

Qemu · Qemu

An infinite loop flaw was found in the e1000 NIC emulator of the QEMU. This issue occurs while processing transmits (tx) descriptors in process_tx_desc if various descriptor fields are initialized with invalid values. This flaw allows a guest to consume CPU cycles on the host, resulting in a denial of service. The highest threat from this vulnerability is to system availability.

6.5 CVSS 3.1 Medium EPSS 0.37% · top 71.7% CWE-835 · CWE-835
6.5CVSS 3.1 base score, v2 2.1
0.37%EPSS exploitation probability, 30 days
NoNot in CISA KEV
8Affected product versions listed by NVD
14References
17 Jun 2026Last modified by NVD

Description

An infinite loop flaw was found in the e1000 NIC emulator of the QEMU. This issue occurs while processing transmits (tx) descriptors in process_tx_desc if various descriptor fields are initialized with invalid values. This flaw allows a guest to consume CPU cycles on the host, resulting in a denial of service. The highest threat from this vulnerability is to system availability.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

Affected products

8 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://bugzilla.redhat.com/show_bug.cgi?id=1930087 Issue TrackingPatchThird Party Advisory
https://github.com/qemu/qemu/commit/3de46e6fc489c52c9431a8a832ad8170a7569bd8 PatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2022/09/msg00008.html Mailing ListThird Party Advisory
https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg07428.html Mailing ListPatchVendor Advisory
https://security.gentoo.org/glsa/202208-27 Third Party Advisory
https://security.netapp.com/advisory/ntap-20220425-0003/ Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/02/25/2 Mailing ListPatchThird Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1930087 Issue TrackingPatchThird Party Advisory
https://github.com/qemu/qemu/commit/3de46e6fc489c52c9431a8a832ad8170a7569bd8 PatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2022/09/msg00008.html Mailing ListThird Party Advisory
https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg07428.html Mailing ListPatchVendor Advisory
https://security.gentoo.org/glsa/202208-27 Third Party Advisory
https://security.netapp.com/advisory/ntap-20220425-0003/ Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/02/25/2 Mailing ListPatchThird Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2021-20257), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.