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UBUNTU-CVE-2021-28691 High

UBUNTU-CVE-2021-28691

Guest triggered use-after-free in Linux xen-netback A malicious or buggy network PV frontend can force Linux netback to disable the interface and terminate the receive kernel thread associated with queue 0 in response to the frontend sending a malformed packet. Such kernel thread termination will lead to a use-after-free in Linux netback when the backend is destroyed, as the kernel thread associated with queue 0 will have already exited and thus the call to kthread_stop will be performed against a stale pointer.

Exploit probability Not scored
Published June 29, 2021
Required by Not available
Last source change February 4, 2026

02 / AFFECTED SOFTWARE

Affected packages

Ubuntu:16.04:LTS linux-hwe-edge

23 explicit affected versions

Ubuntu:18.04:LTS linux-aws-5.0

6 explicit affected versions

Ubuntu:18.04:LTS linux-aws-5.3

10 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-azure-edge

4 explicit affected versions

Ubuntu:18.04:LTS linux-gcp

38 explicit affected versions

Ubuntu:18.04:LTS linux-gcp-5.3

13 explicit affected versions

Ubuntu:18.04:LTS linux-oracle-5.0

7 explicit affected versions

Ubuntu:18.04:LTS linux-gcp-edge

12 explicit affected versions

Ubuntu:18.04:LTS linux-gke-4.15

33 explicit affected versions

Ubuntu:18.04:LTS linux-hwe

43 explicit affected versions

Ubuntu:18.04:LTS linux-hwe-edge

10 explicit affected versions

Ubuntu:18.04:LTS linux-oem

50 explicit affected versions

Ubuntu:18.04:LTS linux-oracle-5.3

9 explicit affected versions

Ubuntu:20.04:LTS linux-aws-5.11

2 explicit affected versions

Ubuntu:20.04:LTS linux-aws-5.8

3 explicit affected versions

Ubuntu:20.04:LTS linux-azure-5.11

2 explicit affected versions

Ubuntu:20.04:LTS linux-azure-5.8

3 explicit affected versions

Ubuntu:20.04:LTS linux-gcp-5.11

2 explicit affected versions

Ubuntu:20.04:LTS linux-gcp-5.8

3 explicit affected versions

Ubuntu:20.04:LTS linux-hwe-5.11

3 explicit affected versions

Ubuntu:20.04:LTS linux-hwe-5.8

21 explicit affected versions

Ubuntu:20.04:LTS linux-oem-5.10

16 explicit affected versions

Ubuntu:20.04:LTS linux-riscv-5.11

1 explicit affected versions

Ubuntu:20.04:LTS linux-oem-5.6

29 explicit affected versions

Ubuntu:20.04:LTS linux-oracle-5.11

2 explicit affected versions

Ubuntu:20.04:LTS linux-oracle-5.8

4 explicit affected versions

Ubuntu:20.04:LTS linux-raspi2

6 explicit affected versions

Ubuntu:20.04:LTS linux-riscv

12 explicit affected versions

Ubuntu:20.04:LTS linux-riscv-5.8

10 explicit affected versions

03 / CONNECTIONS

Connected vulnerabilities

04 / EVIDENCE

Source records

Open Source Vulnerabilities UBUNTU-CVE-2021-28691

Guest triggered use-after-free in Linux xen-netback A malicious or buggy network PV frontend can force Linux netback to disable the interface and terminate the receive kernel thread associated with queue 0 in response to the frontend sending a malformed packet. Such kernel thread termination will lead to a use-after-free in Linux netback when the backend is destroyed, as the kernel thread associated with queue 0 will have already exited and thus the call to kthread_stop will be performed against a stale pointer.

View original source

05 / REFERENCES

Further evidence