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USN-4917-1 Not scored

linux, linux-aws, linux-aws-5.4, linux-azure, linux-azure-5.4, linux-gcp, linux-gcp-5.4, linux-gke-5.3, linux-gke-5.4, linux-gkeop, linux-gkeop-5.4, linux-hwe, linux-hwe-5.4, linux-hwe-5.8, linux-kvm, linux-oem-5.10, linux-oracle, linux-oracle-5.4, linux-raspi, linux-raspi-5.4, linux-raspi2-5.3 vulnerabilities

It was discovered that the overlayfs implementation in the Linux kernel did not properly validate the application of file system capabilities with respect to user namespaces. A local attacker could use this to gain elevated privileges. (CVE-2021-3493) Vincent Dehors discovered that the shiftfs file system in the Ubuntu Linux kernel did not properly handle faults in copy_from_user() when passing through ioctls to an underlying file system. A local attacker could use this to cause a denial of service (memory exhaustion) or execute arbitrary code. (CVE-2021-3492) Piotr Krysiuk discovered that the BPF JIT compiler for x86 in the Linux kernel did not properly validate computation of branch displacements in some situations. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2021-29154)

Exploit probability Not scored
Published April 15, 2021
Required by Not available
Last source change June 3, 2026

02 / AFFECTED SOFTWARE

Affected packages

Ubuntu:18.04:LTS linux-aws-5.4

16 explicit affected versions

Ubuntu:18.04:LTS linux-azure-5.4

15 explicit affected versions

Ubuntu:18.04:LTS linux-gcp-5.4

16 explicit affected versions

Ubuntu:18.04:LTS linux-gke-5.3

17 explicit affected versions

Ubuntu:18.04:LTS linux-gke-5.4

11 explicit affected versions

Ubuntu:18.04:LTS linux-gkeop-5.4

11 explicit affected versions

Ubuntu:18.04:LTS linux-hwe

39 explicit affected versions

Ubuntu:18.04:LTS linux-hwe-5.4

22 explicit affected versions

Ubuntu:18.04:LTS linux-oracle-5.4

16 explicit affected versions

Ubuntu:18.04:LTS linux-raspi-5.4

15 explicit affected versions

Ubuntu:18.04:LTS linux-raspi2-5.3

16 explicit affected versions

Ubuntu:20.04:LTS linux

34 explicit affected versions

Ubuntu:20.04:LTS linux-aws

28 explicit affected versions

Ubuntu:20.04:LTS linux-azure

25 explicit affected versions

Ubuntu:20.04:LTS linux-gcp

26 explicit affected versions

Ubuntu:20.04:LTS linux-gkeop

6 explicit affected versions

Ubuntu:20.04:LTS linux-hwe-5.8

16 explicit affected versions

Ubuntu:20.04:LTS linux-kvm

24 explicit affected versions

Ubuntu:20.04:LTS linux-oem-5.10

8 explicit affected versions

Ubuntu:20.04:LTS linux-oracle

26 explicit affected versions

Ubuntu:20.04:LTS linux-raspi

19 explicit affected versions

03 / CONNECTIONS

Connected vulnerabilities

04 / EVIDENCE

Source records

Open Source Vulnerabilities USN-4917-1

It was discovered that the overlayfs implementation in the Linux kernel did not properly validate the application of file system capabilities with respect to user namespaces. A local attacker could use this to gain elevated privileges. (CVE-2021-3493) Vincent Dehors discovered that the shiftfs file system in the Ubuntu Linux kernel did not properly handle faults in copy_from_user() when passing through ioctls to an underlying file system. A local attacker could use this to cause a denial of service (memory exhaustion) or execute arbitrary code. (CVE-2021-3492) Piotr Krysiuk discovered that the BPF JIT compiler for x86 in the Linux kernel did not properly validate computation of branch displacements in some situations. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2021-29154)

View original source

05 / REFERENCES

Further evidence