CVE-2021-20322

kernel: new DNS Cache Poisoning Attack based on ICMP fragment needed packets replies

Published Feb 18, 2022 CVSS 3.1 · 7.4 High EPSS 6.9% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-2843-1 linux security update
Debian DLA Debian DLA DLA-2941-1 linux-4.19 security update
Debian DSA Debian DSA DSA-5096-1 linux security update
EUVD EUVD EUVD-2021-7746 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.
Ubuntu USN Ubuntu USN USN-5268-1 Linux kernel vulnerabilities
History

No history.

Weaknesses

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Jul 30, 2026, 3:52 PM
Reserved
Dec 17, 2020, 12:00 AM
Status
Analyzed
Published
Feb 18, 2022, 6:15 PM
Modified
Jul 30, 2026, 7:33 PM
Severity
Moderate
Public date
Aug 26, 2021, 8:00 AM