UBUNTU-CVE-2026-99263

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    UBUNTU-CVE-2026-99263

    Published: 3 Nov 2026Last Modified: 6 Nov 2026
    Upstream:
    CVE-2026-99263

    Summary:

    Details: In the Linux kernel, the following vulnerability has been resolved: io_uring/poll: avoid retry wakeup loss when dropping ownership If a wakeup sets IO_POLL_RETRY_FLAG between the owning task consuming the existing instance of IO_POLL_RETRY_FLAG and the loop check of io_poll_check_events(), then we stall on processing the request until an unrelated wakeup comes along. Using atomic_cmpxchg instead of atomic_sub_return to guarantee both the count v and poll_refs are 0 and no wake-ups are missed.

    References: https://ubuntu.com/security/CVE-2026-99263, https://www.cve.org/CVERecord?id=CVE-2026-99263, https://git.kernel.org/stable/c/eb2a50d8235e4580fea9aa20f3fbe1a002c38cb1, https://git.kernel.org/stable/c/41fae2e9e1fa3bee86aee0a25ba90e59ce5024bf, https://git.kernel.org/stable/c/521e8a65e9b45532295ba1082ef12be6e80c173b, https://git.kernel.org/stable/c/d1f6850086ac6f8b0fa44fb19aa2a468c73ee071, https://git.kernel.org/stable/c/4ef685b8505615729d75c875f52822238bf76ca6, https://git.kernel.org/stable/c/afa407c02f3aa0fd872f86c9bf1b34502e0fa8f0

    Affected packages

    Package

    Name: linux-hwe-edge

    Purl: pkg:deb/ubuntu/linux-hwe-edge?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-2026-99263 | CVE-DB