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UBUNTU-CVE-2021-33909 High

UBUNTU-CVE-2021-33909

fs/seq_file.c in the Linux kernel 3.16 through 5.13.x before 5.13.4 does not properly restrict seq buffer allocations, leading to an integer overflow, an Out-of-bounds Write, and escalation to root by an unprivileged user, aka CID-8cae8cd89f05.

Exploit probability Not scored
Published July 20, 2021
Required by Not available
Last source change August 17, 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

1 explicit affected versions

Ubuntu:20.04:LTS linux-raspi2

6 explicit affected versions

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

2 explicit affected versions

Ubuntu:18.04:LTS linux-aws

67 explicit affected versions

Ubuntu:20.04:LTS linux-kvm

28 explicit affected versions

Ubuntu:18.04:LTS linux-oracle

47 explicit affected versions

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

20 explicit affected versions

Ubuntu:18.04:LTS linux

77 explicit affected versions

Ubuntu:20.04:LTS linux-aws-5.8

2 explicit affected versions

Ubuntu:16.04:LTS linux-hwe-edge

23 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-kvm

64 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

20 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

1 explicit affected versions

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

1 explicit affected versions

Ubuntu:20.04:LTS linux-gcp

30 explicit affected versions

Ubuntu:20.04:LTS linux

38 explicit affected versions

Ubuntu:20.04:LTS linux-oracle-5.11

1 explicit affected versions

Ubuntu:20.04:LTS linux-azure

30 explicit affected versions

Ubuntu:18.04:LTS linux-gcp-4.15

22 explicit affected versions

Ubuntu:18.04:LTS linux-hwe-edge

10 explicit affected versions

Ubuntu:Pro:16.04:LTS linux

129 explicit affected versions

Ubuntu:18.04:LTS linux-gke-5.4

15 explicit affected versions

Ubuntu:Pro:14.04:LTS linux-aws

63 explicit affected versions

Ubuntu:18.04:LTS linux-snapdragon

44 explicit affected versions

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

1 explicit affected versions

Ubuntu:20.04:LTS linux-oem-5.10

16 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-gke-5.3

20 explicit affected versions

Ubuntu:18.04:LTS linux-kvm

61 explicit affected versions

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

1 explicit affected versions

Ubuntu:20.04:LTS linux-aws

33 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-aws-hwe

46 explicit affected versions

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

11 explicit affected versions

Ubuntu:20.04:LTS linux-hwe-5.11

1 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-gcp

69 explicit affected versions

Ubuntu:20.04:LTS linux-azure-5.8

2 explicit affected versions

Ubuntu:20.04:LTS linux-oracle

31 explicit affected versions

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

2 explicit affected versions

Ubuntu:18.04:LTS linux-raspi2

64 explicit affected versions

Ubuntu:18.04:LTS linux-hwe-5.4

26 explicit affected versions

Ubuntu:Pro:14.04:LTS linux

161 explicit affected versions

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

1 explicit affected versions

Ubuntu:20.04:LTS linux-gke

10 explicit affected versions

Ubuntu:18.04:LTS linux-azure-4.15

23 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

26 explicit affected versions

Ubuntu:20.04:LTS linux-oracle-5.8

3 explicit affected versions

Ubuntu:18.04:LTS linux-gcp-5.4

20 explicit affected versions

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

1 explicit affected versions

Ubuntu:18.04:LTS linux-aws-5.4

21 explicit affected versions

Ubuntu:20.04:LTS linux-azure-5.11

1 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

23 explicit affected versions

Ubuntu:20.04:LTS linux-riscv-5.8

10 explicit affected versions

Ubuntu:18.04:LTS linux-raspi-5.4

19 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:18.04:LTS linux-gkeop-5.4

15 explicit affected versions

Ubuntu:18.04:LTS linux-raspi2-5.3

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

107 explicit affected versions

Ubuntu:18.04:LTS linux-oracle-5.4

21 explicit affected versions

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

42 explicit affected versions

Ubuntu:20.04:LTS linux-bluefield

4 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-azure

77 explicit affected versions

Ubuntu:Pro:14.04:LTS linux-azure

54 explicit affected versions

Ubuntu:20.04:LTS linux-gcp-5.8

2 explicit affected versions

Ubuntu:18.04:LTS linux-dell300x

13 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-oracle

45 explicit affected versions

Ubuntu:18.04:LTS linux-azure-5.4

20 explicit affected versions

Ubuntu:18.04:LTS linux-hwe

42 explicit affected versions

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

1 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-aws

85 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-hwe

92 explicit affected versions

Ubuntu:18.04:LTS linux-gcp-edge

12 explicit affected versions

Ubuntu:20.04:LTS linux-raspi

23 explicit affected versions

Ubuntu:18.04:LTS linux-azure-edge

4 explicit affected versions

Ubuntu:20.04:LTS linux-gkeop

10 explicit affected versions

Ubuntu:22.04:LTS linux-realtime

1 explicit affected versions

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

1 explicit affected versions

03 / CONNECTIONS

Connected vulnerabilities

04 / EVIDENCE

Source records

Open Source Vulnerabilities UBUNTU-CVE-2021-33909

fs/seq_file.c in the Linux kernel 3.16 through 5.13.x before 5.13.4 does not properly restrict seq buffer allocations, leading to an integer overflow, an Out-of-bounds Write, and escalation to root by an unprivileged user, aka CID-8cae8cd89f05.

View original source

05 / REFERENCES

Further evidence