UBUNTU-CVE-2021-28691

Advisory lineage Upstream: 1 Downstream: 3
Upstream
CVE-2021-28691
Published: 29 Jun 2021, 12:15
Last modified:04 Feb 2026, 02:28

Vulnerability Summary

Overall Risk (default)
medium
31/100
CVSS Score
7.8 HIGH
3.1 (osv_ubuntu)
EPSS Score
No data
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

29 Jun 2021, 12:15
Published
Vulnerability first disclosed
04 Feb 2026, 02:28
Last Modified
Vulnerability information updated

Description

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.

CVSS Metrics

  • v3.1•HIGH•Score: 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected Systems

  • ubuntu•linux-aws-5.0

    all

  • ubuntu•linux-aws-5.11

    < 5.11.0-1016.17~20.04.1

  • ubuntu•linux-aws-5.3

    all

  • ubuntu•linux-aws-5.8

    < 5.8.0-1042.44~20.04.1

  • ubuntu•linux-azure

    all

  • ubuntu•linux-azure-5.11

    < 5.11.0-1013.14~20.04.1

  • ubuntu•linux-azure-5.3

    all

  • ubuntu•linux-azure-5.8

    < 5.8.0-1040.43~20.04.1

  • ubuntu•linux-azure-edge

    all

  • ubuntu•linux-gcp

    all

  • ubuntu•linux-gcp-5.11

    < 5.11.0-1017.19~20.04.1

  • ubuntu•linux-gcp-5.3

    all

  • ubuntu•linux-gcp-5.8

    < 5.8.0-1039.41

  • ubuntu•linux-gcp-edge

    all

  • ubuntu•linux-gke-4.15

    all

  • ubuntu•linux-hwe

    all

  • ubuntu•linux-hwe-5.11

    < 5.11.0-34.36~20.04.1

  • ubuntu•linux-hwe-5.8

    all

  • ubuntu•linux-hwe-edge

    all | all

  • ubuntu•linux-oem

    all

  • ubuntu•linux-oem-5.10

    < 5.10.0-1038.40

  • ubuntu•linux-oem-5.6

    all

  • ubuntu•linux-oracle-5.0

    all

  • ubuntu•linux-oracle-5.11

    < 5.11.0-1016.17~20.04.1

  • ubuntu•linux-oracle-5.3

    all

  • ubuntu•linux-oracle-5.8

    < 5.8.0-1038.39~20.04.1

  • ubuntu•linux-raspi2

    all

  • ubuntu•linux-riscv

    all

  • ubuntu•linux-riscv-5.11

    < 5.11.0-1017.18~20.04.1

  • ubuntu•linux-riscv-5.8

    all

References (6)