CVE-2021-20322
CWE-330Published: February 18, 2022· Updated: Jun 17, 2026
Official 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.
Technical Analysis
CVE-2021-20322 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.
A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), with a CVSS base score of 7.4.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
Official Patches & Advisories
All References (18)
Quick Facts
Related CVEs (CWE-330)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-20322 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts