CVE-2021-20322

Name: CVE-2021-20322
Creator: NVD / NIST
Published: 2022-02-18T18:15:09.013+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.4/10EPSS 6.90%

Last modified Jun 17, 2026

CVE-2021-20322 is a high-severity vulnerability rated 7.4/10 on the CVSS scale. A flaw in the processing of received ICMP errors (ICMP fragment needed and ICMP redirect) in the Linux kernel functionality was found to allow the ability to quickly scan open UDP ports. This flaw allows an off-path remote user to effectively bypass the source port UDP randomization. EPSS estimates a 6.90% chance of exploitation in the next 30 days.

Description

A flaw in the processing of received ICMP errors (ICMP fragment needed and ICMP redirect) in the Linux kernel functionality was found to allow the ability to quickly scan open UDP ports. This flaw allows an off-path remote user to effectively bypass the source port UDP randomization. The highest threat from this vulnerability is to confidentiality and possibly integrity, because software that relies on UDP source port randomization are indirectly affected as well.

Metrics

CVSS 3.1

7.4/10

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

EPSS Probability

6.90%

93.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Linux	Linux Kernel	<= 5.14.21
Fedoraproject	Fedora	34
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0
Netapp	Active Iq Unified Manager	All versions
Netapp	E-Series Santricity Os Controller	>= 11.0, <= 11.70.1
Netapp	Solidfire\, Enterprise Sds \& Hci Storage Node	All versions
Netapp	Solidfire \& Hci Management Node	All versions
Netapp	Fas Baseboard Management Controller Firmware	All versions
Netapp	Aff Baseboard Management Controller Firmware	All versions
Netapp	Aff A700s Firmware	All versions
Netapp	H700s Firmware	All versions
Netapp	H700e Firmware	All versions
Netapp	H500s Firmware	All versions
Netapp	H410s Firmware	All versions
Netapp	H500e Firmware	All versions
Netapp	H300e Firmware	All versions
Netapp	H300s Firmware	All versions
Netapp	Hci Compute Node Firmware	All versions
Oracle	Communications Cloud Native Core Binding Support Function	22.1.3
Oracle	Communications Cloud Native Core Network Exposure Function	22.1.1
Oracle	Communications Cloud Native Core Policy	22.2.0

References

https://bugzilla.redhat.com/show_bug.cgi?id=2014230Issue Tracking, Third Party Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.15-rc6&id=4785305c05b25a242e5314cc821f54ade4c18810Mailing List, Patch, Vendor Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.15-rc6&id=6457378fe796815c973f631a1904e147d6ee33b1Mailing List, Patch, Vendor Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/ipv4/route.c?h=v5.15-rc6&id=67d6d681e15b578c1725bad8ad079e05d1c48a8eMailing List, Patch, Vendor Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/ipv6/route.c?h=v5.15-rc6&id=a00df2caffed3883c341d5685f830434312e4a43Mailing List, Patch, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2022/03/msg00012.htmlMailing List, Third Party Advisory
https://security.netapp.com/advisory/ntap-20220303-0002/Third Party Advisory
https://www.debian.org/security/2022/dsa-5096Third Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.htmlThird Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2014230Issue Tracking, Third Party Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.15-rc6&id=4785305c05b25a242e5314cc821f54ade4c18810Mailing List, Patch, Vendor Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.15-rc6&id=6457378fe796815c973f631a1904e147d6ee33b1Mailing List, Patch, Vendor Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/ipv4/route.c?h=v5.15-rc6&id=67d6d681e15b578c1725bad8ad079e05d1c48a8eMailing List, Patch, Vendor Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/ipv6/route.c?h=v5.15-rc6&id=a00df2caffed3883c341d5685f830434312e4a43Mailing List, Patch, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2022/03/msg00012.htmlMailing List, Third Party Advisory
https://security.netapp.com/advisory/ntap-20220303-0002/Third Party Advisory
https://www.debian.org/security/2022/dsa-5096Third Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.htmlThird Party Advisory

Timeline

Published: Feb 18, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-20322?

How severe is CVE-2021-20322?

CVE-2021-20322 has a CVSS score of 7.4/10 (HIGH severity). The EPSS model estimates a 6.90% probability of exploitation in the next 30 days.

How do I fix CVE-2021-20322?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-20322?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST