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UBUNTU-CVE-2021-20322 High

UBUNTU-CVE-2021-20322

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.

Exploit probability Not scored
Published October 19, 2021
Required by Not available
Last source change August 19, 2026

02 / AFFECTED SOFTWARE

Affected packages

Ubuntu:18.04:LTS linux-oem

50 explicit affected versions

Ubuntu:18.04:LTS linux-aws-5.0

6 explicit affected versions

Ubuntu:20.04:LTS linux-aws-5.11

6 explicit affected versions

Ubuntu:20.04:LTS linux-raspi2

6 explicit affected versions

Ubuntu:Pro:FIPS-updates:20.04:LTS linux-fips

9 explicit affected versions

Ubuntu:Pro:14.04:LTS linux

191 explicit affected versions

Ubuntu:18.04:LTS linux-aws

75 explicit affected versions

Ubuntu:20.04:LTS linux-kvm

35 explicit affected versions

Ubuntu:18.04:LTS linux-oracle

55 explicit affected versions

Ubuntu:Pro:FIPS-updates:18.04:LTS linux-azure-fips

28 explicit affected versions

Ubuntu:18.04:LTS linux

87 explicit affected versions

Ubuntu:20.04:LTS linux-aws-5.8

4 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-kvm

121 explicit affected versions

Ubuntu:16.04:LTS linux-hwe-edge

23 explicit affected versions

Ubuntu:Pro:FIPS:18.04:LTS linux-gcp-fips

1 explicit affected versions

Ubuntu:24.04:LTS linux-raspi-realtime

1 explicit affected versions

Ubuntu:20.04:LTS linux-hwe-5.8

21 explicit affected versions

Ubuntu:Pro:FIPS-updates:20.04:LTS linux-aws-fips

1 explicit affected versions

Ubuntu:18.04:LTS linux-oracle-5.0

7 explicit affected versions

Ubuntu:20.04:LTS linux-riscv

12 explicit affected versions

Ubuntu:20.04:LTS linux-gcp-5.11

6 explicit affected versions

Ubuntu:22.04:LTS linux-intel-iot-realtime

1 explicit affected versions

Ubuntu:20.04:LTS linux-intel-5.13

7 explicit affected versions

Ubuntu:20.04:LTS linux-oem-5.13

5 explicit affected versions

Ubuntu:20.04:LTS linux-gcp

38 explicit affected versions

Ubuntu:20.04:LTS linux

46 explicit affected versions

Ubuntu:20.04:LTS linux-oracle-5.11

6 explicit affected versions

Ubuntu:20.04:LTS linux-azure

38 explicit affected versions

Ubuntu:Pro:14.04:LTS linux-aws

120 explicit affected versions

Ubuntu:18.04:LTS linux-gcp-4.15

30 explicit affected versions

Ubuntu:18.04:LTS linux-hwe-edge

10 explicit affected versions

Ubuntu:18.04:LTS linux-gke-5.4

22 explicit affected versions

Ubuntu:18.04:LTS linux-snapdragon

53 explicit affected versions

Ubuntu:Pro:FIPS:20.04:LTS linux-aws-fips

1 explicit affected versions

Ubuntu:20.04:LTS linux-oem-5.10

20 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-aws

144 explicit affected versions

Ubuntu:Pro:FIPS:18.04:LTS linux-fips

1 explicit affected versions

Ubuntu:20.04:LTS linux-oem-5.6

29 explicit affected versions

Ubuntu:18.04:LTS linux-gcp-5.3

13 explicit affected versions

Ubuntu:18.04:LTS linux-kvm

69 explicit affected versions

Ubuntu:Pro:FIPS:18.04:LTS linux-azure-fips

1 explicit affected versions

Ubuntu:20.04:LTS linux-aws

40 explicit affected versions

Ubuntu:18.04:LTS linux-gke-4.15

33 explicit affected versions

Ubuntu:18.04:LTS linux-aws-5.3

10 explicit affected versions

Ubuntu:Pro:16.04:LTS linux

188 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-aws-hwe

54 explicit affected versions

Ubuntu:Nvidia-BlueField:24.04:LTS linux-bluefield

11 explicit affected versions

Ubuntu:20.04:LTS linux-hwe-5.11

12 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-gcp

77 explicit affected versions

Ubuntu:20.04:LTS linux-azure-5.8

7 explicit affected versions

Ubuntu:20.04:LTS linux-oracle

38 explicit affected versions

Ubuntu:Pro:FIPS:16.04:LTS linux-fips

2 explicit affected versions

Ubuntu:18.04:LTS linux-raspi2

73 explicit affected versions

Ubuntu:Pro:14.04:LTS linux-lts-xenial

165 explicit affected versions

Ubuntu:18.04:LTS linux-hwe-5.4

34 explicit affected versions

Ubuntu:Pro:FIPS:20.04:LTS linux-azure-fips

1 explicit affected versions

Ubuntu:20.04:LTS linux-ibm

6 explicit affected versions

Ubuntu:20.04:LTS linux-gke

17 explicit affected versions

Ubuntu:18.04:LTS linux-azure-4.15

32 explicit affected versions

Ubuntu:Pro:FIPS:18.04:LTS linux-aws-fips

1 explicit affected versions

Ubuntu:Pro:FIPS:20.04:LTS linux-fips

1 explicit affected versions

Ubuntu:Pro:FIPS-updates:18.04:LTS linux-fips

35 explicit affected versions

Ubuntu:20.04:LTS linux-oracle-5.8

5 explicit affected versions

Ubuntu:18.04:LTS linux-gcp-5.4

28 explicit affected versions

Ubuntu:Pro:FIPS:20.04:LTS linux-gcp-fips

1 explicit affected versions

Ubuntu:18.04:LTS linux-aws-5.4

28 explicit affected versions

Ubuntu:20.04:LTS linux-azure-5.11

7 explicit affected versions

Ubuntu:Pro:FIPS-updates:20.04:LTS linux-azure-fips

1 explicit affected versions

Ubuntu:Pro:FIPS-updates:18.04:LTS linux-aws-fips

31 explicit affected versions

Ubuntu:20.04:LTS linux-riscv-5.8

10 explicit affected versions

Ubuntu:18.04:LTS linux-raspi-5.4

26 explicit affected versions

Ubuntu:18.04:LTS linux-azure

44 explicit affected versions

Ubuntu:18.04:LTS linux-azure-5.3

16 explicit affected versions

Ubuntu:20.04:LTS linux-riscv-5.11

5 explicit affected versions

Ubuntu:18.04:LTS linux-gkeop-5.4

22 explicit affected versions

Ubuntu:18.04:LTS linux-gcp

38 explicit affected versions

Ubuntu:18.04:LTS linux-oracle-5.3

9 explicit affected versions

Ubuntu:18.04:LTS linux-oracle-5.4

28 explicit affected versions

Ubuntu:Pro:FIPS:16.04:LTS linux-fips

97 explicit affected versions

Ubuntu:20.04:LTS linux-bluefield

9 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-azure

85 explicit affected versions

Ubuntu:Pro:14.04:LTS linux-azure

62 explicit affected versions

Ubuntu:20.04:LTS linux-gcp-5.8

4 explicit affected versions

Ubuntu:18.04:LTS linux-dell300x

19 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-oracle

53 explicit affected versions

Ubuntu:18.04:LTS linux-azure-5.4

28 explicit affected versions

Ubuntu:18.04:LTS linux-hwe

43 explicit affected versions

Ubuntu:Pro:FIPS-updates:20.04:LTS linux-gcp-fips

1 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-hwe

102 explicit affected versions

Ubuntu:20.04:LTS linux-raspi

30 explicit affected versions

Ubuntu:18.04:LTS linux-azure-edge

4 explicit affected versions

Ubuntu:20.04:LTS linux-gkeop

17 explicit affected versions

Ubuntu:22.04:LTS linux-realtime

1 explicit affected versions

Ubuntu:Pro:FIPS-updates:18.04:LTS linux-gcp-fips

9 explicit affected versions

03 / CONNECTIONS

Connected vulnerabilities

04 / EVIDENCE

Source records

Open Source Vulnerabilities UBUNTU-CVE-2021-20322

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.

View original source

05 / REFERENCES

Further evidence