UBUNTU-CVE-2021-28691

    Dashboard / Vulnerabilities / UBUNTU-CVE-2021-28691

    UBUNTU-CVE-2021-28691

    Published: 29 Jun 2021Last Modified: 4 Feb 2026
    Upstream:
    CVE-2021-28691

    Summary:

    Details: 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.

    References: https://ubuntu.com/security/CVE-2021-28691, https://xenbits.xen.org/xsa/advisory-374.html, https://ubuntu.com/security/notices/USN-5015-1, https://ubuntu.com/security/notices/USN-5046-1, https://ubuntu.com/security/notices/USN-5050-1, https://www.cve.org/CVERecord?id=CVE-2021-28691

    Affected packages

    Package

    Name: linux-hwe-edge

    Purl: pkg:deb/ubuntu/[email protected]~16.04.1?arch=source&distro=xenial

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -None

    Affected versions

    4.8.0-28.30~16.04.1
    4.8.0-30.32~16.04.1
    4.8.0-32.34~16.04.1
    4.8.0-34.36~16.04.1

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    UBUNTU-CVE-2021-28691 | CVE-DB