Is CVE-2021-20321 in the CISA KEV catalog?

No. CVE-2021-20321 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-20321?

CVE-2021-20321 has a CVSS v3 base score of 4.7 (MEDIUM).

What is the EPSS score for CVE-2021-20321?

CVE-2021-20321 has an EPSS score of 0.21% (12th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-20321?

Upgrade linux on debian 11 to 5.10.84-1 or later. Fixes are available for 120 affected products.

CVE & CISA-KEV Catalog

CVE-2021-20321

MEDIUM

4.7

CVSS v3

NVD

Description

A race condition accessing file object in the Linux kernel OverlayFS subsystem was found in the way users do rename in specific way with OverlayFS. A local user could use this flaw to crash the system.

CWE-362Race Condition

How to fix

Remediation Available

linuxDebian

Fixed in:5.10.84-1CVE-2021-20321

Fixed in:5.14.12-1CVE-2021-20321

linuxUbuntu

Fixed in:4.4.0-242.276USN-6221-1

Fixed in:4.15.0-166.174USN-5209-1

Fixed in:5.4.0-92.103USN-5210-1

linux-awsUbuntu

Fixed in:4.4.0-1120.126USN-6221-1

Fixed in:4.4.0-1158.173USN-6221-1

Fixed in:4.15.0-1118.125USN-5209-1

Fixed in:5.4.0-1061.64USN-5210-1

linux-aws-5.11Ubuntu

Fixed in:5.11.0-1023.24~20.04.1USN-5208-1

linux-aws-5.4Ubuntu

Fixed in:5.4.0-1061.64~18.04.1USN-5210-1

linux-aws-hweUbuntu

Fixed in:4.15.0-1118.125~16.04.1USN-5209-1

linux-azureUbuntu

Fixed in:4.15.0-1129.142~14.04.1USN-5209-1

Fixed in:4.15.0-1129.142~16.04.1USN-5209-1

Fixed in:5.4.0-1065.68USN-5210-1

linux-azure-4.15Ubuntu

Fixed in:4.15.0-1129.142USN-5209-1

linux-azure-5.11Ubuntu

Fixed in:5.11.0-1023.24~20.04.1USN-5208-1

linux-azure-5.4Ubuntu

Fixed in:5.4.0-1065.68~18.04.1USN-5210-1

linux-bluefieldUbuntu

Fixed in:5.4.0-1023.26USN-5210-1

linux-dell300xUbuntu

Fixed in:4.15.0-1033.38USN-5209-1

linux-gcpUbuntu

Fixed in:4.15.0-1114.128~16.04.1USN-5209-1

Fixed in:5.4.0-1059.63USN-5210-1

linux-gcp-4.15Ubuntu

Fixed in:4.15.0-1114.128USN-5209-1

linux-gcp-5.11Ubuntu

Fixed in:5.11.0-1024.26~20.04.1USN-5208-1

linux-gcp-5.4Ubuntu

Fixed in:5.4.0-1059.63~18.04.1USN-5210-1

linux-gkeUbuntu

Fixed in:5.4.0-1057.60USN-5210-1

linux-gke-5.4Ubuntu

Fixed in:5.4.0-1057.60~18.04.1USN-5210-1

linux-gkeopUbuntu

Fixed in:5.4.0-1029.30USN-5210-1

linux-gkeop-5.4Ubuntu

Fixed in:5.4.0-1029.30~18.04.2USN-5210-1

linux-hweUbuntu

Fixed in:4.15.0-166.174~16.04.1USN-5209-1

linux-hwe-5.11Ubuntu

Fixed in:5.11.0-44.48~20.04.2USN-5208-1

linux-hwe-5.4Ubuntu

Fixed in:5.4.0-92.103~18.04.2USN-5210-1

linux-ibmUbuntu

Fixed in:5.4.0-1010.11USN-5210-1

linux-image-4.15.0-1033-dell300xUbuntu

Fixed in:4.15.0-1033.38USN-5209-1

linux-image-4.15.0-1085-oracleUbuntu

Fixed in:4.15.0-1085.93~16.04.1USN-5209-1

Fixed in:4.15.0-1085.93USN-5209-1

linux-image-4.15.0-1101-raspi2Ubuntu

Fixed in:4.15.0-1101.108USN-5209-1

linux-image-4.15.0-1105-kvmUbuntu

Fixed in:4.15.0-1105.107USN-5209-1

linux-image-4.15.0-1114-gcpUbuntu

Fixed in:4.15.0-1114.128~16.04.1USN-5209-1

Fixed in:4.15.0-1114.128USN-5209-1

linux-image-4.15.0-1118-awsUbuntu

Fixed in:4.15.0-1118.125~16.04.1USN-5209-1

Fixed in:4.15.0-1118.125USN-5209-1

linux-image-4.15.0-1118-snapdragonUbuntu

Fixed in:4.15.0-1118.127USN-5209-1

linux-image-4.15.0-1129-azureUbuntu

Fixed in:4.15.0-1129.142~14.04.1USN-5209-1

Fixed in:4.15.0-1129.142~16.04.1USN-5209-1

Fixed in:4.15.0-1129.142USN-5209-1

linux-image-4.15.0-166-genericUbuntu

Fixed in:4.15.0-166.174~16.04.1USN-5209-1

Fixed in:4.15.0-166.174USN-5209-1

linux-image-4.15.0-166-generic-lpaeUbuntu

Fixed in:4.15.0-166.174USN-5209-1

linux-image-4.15.0-166-lowlatencyUbuntu

Fixed in:4.15.0-166.174~16.04.1USN-5209-1

Fixed in:4.15.0-166.174USN-5209-1

linux-image-4.4.0-1120-awsUbuntu

Fixed in:4.4.0-1120.126USN-6221-1

linux-image-4.4.0-1121-kvmUbuntu

Fixed in:4.4.0-1121.131USN-6221-1

linux-image-4.4.0-1158-awsUbuntu

Fixed in:4.4.0-1158.173USN-6221-1

linux-image-4.4.0-242-genericUbuntu

Fixed in:4.4.0-242.276~14.04.1USN-6221-1

Fixed in:4.4.0-242.276USN-6221-1

linux-image-4.4.0-242-lowlatencyUbuntu

Fixed in:4.4.0-242.276~14.04.1USN-6221-1

Fixed in:4.4.0-242.276USN-6221-1

linux-image-5.11.0-1023-awsUbuntu

Fixed in:5.11.0-1023.24~20.04.1USN-5208-1

linux-image-5.11.0-1023-azureUbuntu

Fixed in:5.11.0-1023.24~20.04.1USN-5208-1

linux-image-5.11.0-1023-oracleUbuntu

Fixed in:5.11.0-1023.24~20.04.1USN-5208-1

linux-image-5.11.0-1024-gcpUbuntu

Fixed in:5.11.0-1024.26~20.04.1USN-5208-1

linux-image-5.11.0-44-genericUbuntu

Fixed in:5.11.0-44.48~20.04.2USN-5208-1

linux-image-5.11.0-44-generic-64kUbuntu

Fixed in:5.11.0-44.48~20.04.2USN-5208-1

linux-image-5.11.0-44-generic-lpaeUbuntu

Fixed in:5.11.0-44.48~20.04.2USN-5208-1

linux-image-5.11.0-44-lowlatencyUbuntu

Fixed in:5.11.0-44.48~20.04.2USN-5208-1

linux-image-5.13.0-1026-oemUbuntu

Fixed in:5.13.0-1026.32USN-5218-1

linux-image-5.4.0-1010-ibmUbuntu

Fixed in:5.4.0-1010.11USN-5210-1

linux-image-5.4.0-1023-bluefieldUbuntu

Fixed in:5.4.0-1023.26USN-5210-1

linux-image-5.4.0-1029-gkeopUbuntu

Fixed in:5.4.0-1029.30~18.04.2USN-5210-1

Fixed in:5.4.0-1029.30USN-5210-1

linux-image-5.4.0-1048-raspiUbuntu

Fixed in:5.4.0-1048.53~18.04.1USN-5210-1

Fixed in:5.4.0-1048.53USN-5210-1

linux-image-5.4.0-1051-kvmUbuntu

Fixed in:5.4.0-1051.53USN-5210-1

linux-image-5.4.0-1057-gkeUbuntu

Fixed in:5.4.0-1057.60~18.04.1USN-5210-1

Fixed in:5.4.0-1057.60USN-5210-1

linux-image-5.4.0-1059-gcpUbuntu

Fixed in:5.4.0-1059.63~18.04.1USN-5210-1

Fixed in:5.4.0-1059.63USN-5210-1

linux-image-5.4.0-1059-oracleUbuntu

Fixed in:5.4.0-1059.63~18.04.1USN-5210-1

Fixed in:5.4.0-1059.63USN-5210-1

linux-image-5.4.0-1065-azureUbuntu

Fixed in:5.4.0-1065.68~18.04.1USN-5210-1

Fixed in:5.4.0-1065.68USN-5210-1

linux-image-5.4.0-92-genericUbuntu

Fixed in:5.4.0-92.103~18.04.2USN-5210-1

Fixed in:5.4.0-92.103USN-5210-1

linux-image-5.4.0-92-generic-lpaeUbuntu

Fixed in:5.4.0-92.103~18.04.2USN-5210-1

Fixed in:5.4.0-92.103USN-5210-1

linux-image-5.4.0-92-lowlatencyUbuntu

Fixed in:5.4.0-92.103~18.04.2USN-5210-1

Fixed in:5.4.0-92.103USN-5210-1

linux-image-awsUbuntu

Fixed in:4.4.0.1120.117USN-6221-1

Fixed in:4.4.0.1158.162USN-6221-1

Fixed in:5.4.0.1061.44USN-5210-1

Fixed in:5.11.0.1023.24~20.04.23USN-5208-1

linux-image-aws-hweUbuntu

Fixed in:4.15.0.1118.108USN-5209-1

linux-image-aws-lts-18.04Ubuntu

Fixed in:4.15.0.1118.121USN-5209-1

linux-image-aws-lts-20.04Ubuntu

Fixed in:5.4.0.1061.64USN-5210-1

linux-image-azureUbuntu

Fixed in:4.15.0.1129.102USN-5209-1

Fixed in:4.15.0.1129.120USN-5209-1

Fixed in:5.4.0.1065.45USN-5210-1

Fixed in:5.11.0.1023.24~20.04.23USN-5208-1

linux-image-azure-lts-18.04Ubuntu

Fixed in:4.15.0.1129.102USN-5209-1

linux-image-azure-lts-20.04Ubuntu

Fixed in:5.4.0.1065.63USN-5210-1

linux-image-bluefieldUbuntu

Fixed in:5.4.0.1023.24USN-5210-1

linux-image-dell300xUbuntu

Fixed in:4.15.0.1033.35USN-5209-1

linux-image-gcpUbuntu

Fixed in:4.15.0.1114.115USN-5209-1

Fixed in:5.4.0.1059.45USN-5210-1

Fixed in:5.11.0.1024.26~20.04.24USN-5208-1

linux-image-gcp-lts-18.04Ubuntu

Fixed in:4.15.0.1114.133USN-5209-1

linux-image-gcp-lts-20.04Ubuntu

Fixed in:5.4.0.1059.69USN-5210-1

linux-image-genericUbuntu

Fixed in:4.4.0.242.248USN-6221-1

Fixed in:4.15.0.166.155USN-5209-1

Fixed in:5.4.0.92.96USN-5210-1

linux-image-generic-64k-hwe-20.04Ubuntu

Fixed in:5.11.0.44.48~20.04.22USN-5208-1

linux-image-generic-hwe-16.04Ubuntu

Fixed in:4.15.0.166.158USN-5209-1

linux-image-generic-hwe-18.04Ubuntu

Fixed in:5.4.0.92.103~18.04.82USN-5210-1

linux-image-generic-hwe-20.04Ubuntu

Fixed in:5.11.0.44.48~20.04.22USN-5208-1

linux-image-generic-lpaeUbuntu

Fixed in:4.15.0.166.155USN-5209-1

Fixed in:5.4.0.92.96USN-5210-1

linux-image-generic-lpae-hwe-18.04Ubuntu

Fixed in:5.4.0.92.103~18.04.82USN-5210-1

linux-image-generic-lpae-hwe-20.04Ubuntu

Fixed in:5.11.0.44.48~20.04.22USN-5208-1

linux-image-generic-lts-xenialUbuntu

Fixed in:4.4.0.242.210USN-6221-1

Fixed in:4.4.0.242.248USN-6221-1

linux-image-gkeUbuntu

Fixed in:4.15.0.1114.115USN-5209-1

Fixed in:5.4.0.1057.67USN-5210-1

linux-image-gke-5.4Ubuntu

Fixed in:5.4.0.1057.60~18.04.22USN-5210-1

Fixed in:5.4.0.1057.67USN-5210-1

linux-image-gkeopUbuntu

Fixed in:5.4.0.1029.32USN-5210-1

linux-image-gkeop-5.4Ubuntu

Fixed in:5.4.0.1029.30~18.04.30USN-5210-1

Fixed in:5.4.0.1029.32USN-5210-1

linux-image-ibmUbuntu

Fixed in:5.4.0.1010.11USN-5210-1

linux-image-ibm-lts-20.04Ubuntu

Fixed in:5.4.0.1010.11USN-5210-1

linux-image-kvmUbuntu

Fixed in:4.4.0.1121.118USN-6221-1

Fixed in:4.15.0.1105.101USN-5209-1

Fixed in:5.4.0.1051.50USN-5210-1

linux-image-lowlatencyUbuntu

Fixed in:4.4.0.242.248USN-6221-1

Fixed in:4.15.0.166.155USN-5209-1

Fixed in:5.4.0.92.96USN-5210-1

linux-image-lowlatency-hwe-16.04Ubuntu

Fixed in:4.15.0.166.158USN-5209-1

linux-image-lowlatency-hwe-18.04Ubuntu

Fixed in:5.4.0.92.103~18.04.82USN-5210-1

linux-image-lowlatency-hwe-20.04Ubuntu

Fixed in:5.11.0.44.48~20.04.22USN-5208-1

linux-image-lowlatency-lts-xenialUbuntu

Fixed in:4.4.0.242.210USN-6221-1

Fixed in:4.4.0.242.248USN-6221-1

linux-image-oemUbuntu

Fixed in:4.15.0.166.158USN-5209-1

Fixed in:5.4.0.92.103~18.04.82USN-5210-1

Fixed in:5.4.0.92.96USN-5210-1

linux-image-oem-20.04cUbuntu

Fixed in:5.13.0.1026.29USN-5218-1

linux-image-oem-osp1Ubuntu

Fixed in:5.4.0.92.103~18.04.82USN-5210-1

Fixed in:5.4.0.92.96USN-5210-1

linux-image-oracleUbuntu

Fixed in:4.15.0.1085.73USN-5209-1

Fixed in:5.4.0.1059.63~18.04.39USN-5210-1

Fixed in:5.11.0.1023.24~20.04.16USN-5208-1

linux-image-oracle-lts-18.04Ubuntu

Fixed in:4.15.0.1085.95USN-5209-1

linux-image-oracle-lts-20.04Ubuntu

Fixed in:5.4.0.1059.59USN-5210-1

linux-image-raspiUbuntu

Fixed in:5.4.0.1048.83USN-5210-1

linux-image-raspi-hwe-18.04Ubuntu

Fixed in:5.4.0.1048.51USN-5210-1

linux-image-raspi2Ubuntu

Fixed in:4.15.0.1101.99USN-5209-1

Fixed in:5.4.0.1048.83USN-5210-1

linux-image-snapdragonUbuntu

Fixed in:4.15.0.1118.121USN-5209-1

linux-image-snapdragon-hwe-18.04Ubuntu

Fixed in:5.4.0.92.103~18.04.82USN-5210-1

linux-image-virtualUbuntu

Fixed in:4.4.0.242.248USN-6221-1

Fixed in:4.15.0.166.155USN-5209-1

Fixed in:5.4.0.92.96USN-5210-1

linux-image-virtual-hwe-16.04Ubuntu

Fixed in:4.15.0.166.158USN-5209-1

linux-image-virtual-hwe-18.04Ubuntu

Fixed in:5.4.0.92.103~18.04.82USN-5210-1

linux-image-virtual-hwe-20.04Ubuntu

Fixed in:5.11.0.44.48~20.04.22USN-5208-1

linux-image-virtual-lts-xenialUbuntu

Fixed in:4.4.0.242.210USN-6221-1

Fixed in:4.4.0.242.248USN-6221-1

linux-kvmUbuntu

Fixed in:4.4.0-1121.131USN-6221-1

Fixed in:4.15.0-1105.107USN-5209-1

Fixed in:5.4.0-1051.53USN-5210-1

linux-lts-xenialUbuntu

Fixed in:4.4.0-242.276~14.04.1USN-6221-1

linux-oem-5.13Ubuntu

Fixed in:5.13.0-1026.32USN-5218-1

linux-oracleUbuntu

Fixed in:4.15.0-1085.93~16.04.1USN-5209-1

Fixed in:4.15.0-1085.93USN-5209-1

Fixed in:5.4.0-1059.63USN-5210-1

linux-oracle-5.11Ubuntu

Fixed in:5.11.0-1023.24~20.04.1USN-5208-1

linux-oracle-5.4Ubuntu

Fixed in:5.4.0-1059.63~18.04.1USN-5210-1

linux-raspiUbuntu

Fixed in:5.4.0-1048.53USN-5210-1

linux-raspi-5.4Ubuntu

Fixed in:5.4.0-1048.53~18.04.1USN-5210-1

linux-raspi2Ubuntu

Fixed in:4.15.0-1101.108USN-5209-1

linux-snapdragonUbuntu

Fixed in:4.15.0-1118.127USN-5209-1

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 ComplexityHigh

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

0.21%probability of exploitation in 30 days

12thpercentile

Low risk: more likely to be exploited than 12% of all known CVEs.

References

Third-Party Advisory3

Other references1

lore.kernel.org

Related Vulnerabilities

Other CWE-362 (Race Condition) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-6387	High	8.1	100%	-	Fix
CVE-2023-36884	High	7.5	99%	KEV + Ransom	Fix
CVE-2018-15473	Medium	5.3	99%	-	Fix
CVE-2024-27983	High	8.2	87%	-	Fix
CVE-2014-0226	Medium	6.8	86%	-	Fix
CVE-2016-5195	High	7.0	84%	KEV	Fix

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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.