Is CVE-2021-20257 in the CISA KEV catalog?

No. CVE-2021-20257 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-20257?

CVE-2021-20257 has a CVSS v3 base score of 6.5 (MEDIUM).

What is the EPSS score for CVE-2021-20257?

CVE-2021-20257 has an EPSS score of 0.36% (28th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-20257?

Upgrade qemu on debian 11 to 1:5.2+dfsg-9 or later. Fixes are available for 25 affected products.

CVE & CISA-KEV Catalog

CVE-2021-20257

MEDIUM

6.5

CVSS v3

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.

CWE-835

How to fix

Remediation Available

qemuDebian

Fixed in:1:5.2+dfsg-9CVE-2021-20257

qemuUbuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.37USN-5010-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:4.2-3ubuntu6.17USN-5010-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-block-extraUbuntu

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-commonUbuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

qemu-guest-agentUbuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-keymapsUbuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

qemu-kvmUbuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-systemUbuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.37USN-5010-1

Fixed in:1:4.2-3ubuntu6.17USN-5010-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-system-aarch64Ubuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

qemu-system-armUbuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.37USN-5010-1

Fixed in:1:4.2-3ubuntu6.17USN-5010-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-system-commonUbuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-system-dataUbuntu

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-system-guiUbuntu

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-system-mipsUbuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.37USN-5010-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

Fixed in:1:4.2-3ubuntu6.17USN-5010-1

qemu-system-miscUbuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.37USN-5010-1

Fixed in:1:4.2-3ubuntu6.17USN-5010-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-system-ppcUbuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.37USN-5010-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:4.2-3ubuntu6.17USN-5010-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-system-s390xUbuntu

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.37USN-5010-1

Fixed in:1:4.2-3ubuntu6.17USN-5010-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-system-sparcUbuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.37USN-5010-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

Fixed in:1:4.2-3ubuntu6.17USN-5010-1

qemu-system-x86Ubuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.37USN-5010-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

Fixed in:1:4.2-3ubuntu6.17USN-5010-1

qemu-system-x86-microvmUbuntu

Fixed in:1:4.2-3ubuntu6.17USN-5010-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-system-x86-xenUbuntu

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

Fixed in:1:4.2-3ubuntu6.17USN-5010-1

qemu-userUbuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-user-binfmtUbuntu

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-user-staticUbuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

qemu-utilsUbuntu

Fixed in:2.0.0+dfsg-2ubuntu1.47+esm6USN-8412-1

Fixed in:1:2.5+dfsg-5ubuntu10.51+esm4USN-8412-1

Fixed in:1:2.11+dfsg-1ubuntu7.42+esm5USN-8412-1

Fixed in:1:4.2-3ubuntu6.30+esm1USN-8412-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeChanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

0.36%probability of exploitation in 30 days

28thpercentile

Low risk: more likely to be exploited than 28% of all known CVEs.

References

Patch4

Third-Party Advisory3

Related Vulnerabilities

Other CWE-835 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-13935	High	7.5	88%	-	Fix
CVE-2020-36227	High	7.5	78%	-	Fix
CVE-2022-0778	High	7.5	71%	-	Fix
CVE-2019-14241	High	7.5	70%	-	-
CVE-2017-16944	High	7.5	63%	-	Fix
CVE-2024-20353	High	8.6	63%	KEV	-

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.