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Vulnerability record · CVE-2021-20322 · published 18 February 2022

CVE-2021-20322: Linux kernel vulnerability

Linux · Linux Kernel

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.

7.4 CVSS 3.1 High EPSS 6.9% · top 6.1% CWE-330 · CWE-330
7.4CVSS 3.1 base score, v2 5.8
6.9%EPSS exploitation probability, 30 days
NoNot in CISA KEV
21Affected product versions listed by NVD
18References
30 Jul 2026Last modified by NVD

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.

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

Affected products

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

References

LinkTags
https://bugzilla.redhat.com/show_bug.cgi?id=2014230 Issue TrackingThird Party Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.15-rc6&id=4785305c05b25a242e5314cc821f54 Mailing ListPatchVendor Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.15-rc6&id=6457378fe796815c973f631a1904e1 Mailing ListPatchVendor Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/ipv4/route.c?h=v5.15-rc6&id=67d6d681e15b57 Mailing ListPatchVendor Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/ipv6/route.c?h=v5.15-rc6&id=a00df2caffed38 Mailing ListPatchVendor Advisory
https://lists.debian.org/debian-lts-announce/2022/03/msg00012.html Mailing ListThird Party Advisory
https://security.netapp.com/advisory/ntap-20220303-0002/ Third Party Advisory
https://www.debian.org/security/2022/dsa-5096 Third Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.html Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2014230 Issue TrackingThird Party Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.15-rc6&id=4785305c05b25a242e5314cc821f54 Mailing ListPatchVendor Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.15-rc6&id=6457378fe796815c973f631a1904e1 Mailing ListPatchVendor Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/ipv4/route.c?h=v5.15-rc6&id=67d6d681e15b57 Mailing ListPatchVendor Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/ipv6/route.c?h=v5.15-rc6&id=a00df2caffed38 Mailing ListPatchVendor Advisory
https://lists.debian.org/debian-lts-announce/2022/03/msg00012.html Mailing ListThird Party Advisory
https://security.netapp.com/advisory/ntap-20220303-0002/ Third Party Advisory
https://www.debian.org/security/2022/dsa-5096 Third Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.html Third Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2021-20322), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.