UBUNTU-CVE-2026-64534

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    UBUNTU-CVE-2026-64534

    Published: 27 Jul 2026Last Modified: 6 Nov 2026
    Upstream:
    CVE-2026-64534
    Aliases:
    USN-8781-1
    USN-8816-1
    USN-8816-2

    Summary:

    Details: In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: check INIT_FAILED before nvmet_req_uninit in digest error path In nvmet_tcp_try_recv_ddgst(), when a data digest mismatch is detected, nvmet_req_uninit() is called unconditionally. However, if the command arrived via the nvmet_tcp_handle_req_failure() path, nvmet_req_init() had returned false and percpu_ref_tryget_live() was never executed. The unconditional percpu_ref_put() inside nvmet_req_uninit() then causes a refcount underflow, leading to a WARNING in percpu_ref_switch_to_atomic_rcu, a use-after-free diagnostic, and eventually a permanent workqueue deadlock. Check cmd->flags & NVMET_TCP_F_INIT_FAILED before calling nvmet_req_uninit(), matching the existing pattern in nvmet_tcp_execute_request().

    References: https://ubuntu.com/security/CVE-2026-64534, https://www.cve.org/CVERecord?id=CVE-2026-64534, https://git.kernel.org/linus/4606467a75cfc16721937272ed29462a750b60c8, https://git.kernel.org/stable/c/22ec7a9fe9153d2737ee9b2fa6d2e43a1491decf, https://git.kernel.org/stable/c/2ed3c9d955e8cd6361f130623baa664a75fb345f, https://git.kernel.org/stable/c/4606467a75cfc16721937272ed29462a750b60c8, https://git.kernel.org/stable/c/ba35b1c674ca3841c0dfadd698f2c1b3ec542d4e, https://git.kernel.org/stable/c/c7874dad84b20433c0fe3919f291a762d40de08b, https://git.kernel.org/stable/c/d306da8833e75f669d93424fd84940236f3850bc, https://git.kernel.org/stable/c/e602c93b25bda4a9d0ff1791a4bdbfdcbb074af1, https://ubuntu.com/security/notices/USN-8781-1, https://ubuntu.com/security/notices/USN-8816-1, https://ubuntu.com/security/notices/USN-8816-2, https://ubuntu.com/security/notices/USN-8816-3, https://ubuntu.com/security/notices/USN-8816-4, https://ubuntu.com/security/notices/USN-8876-1, https://ubuntu.com/security/notices/USN-8878-1, https://ubuntu.com/security/notices/USN-8879-1, https://ubuntu.com/security/notices/USN-8877-1, https://ubuntu.com/security/notices/USN-8875-1, https://ubuntu.com/security/notices/USN-8888-1, https://ubuntu.com/security/notices/USN-8888-2, https://ubuntu.com/security/notices/USN-8875-2, https://ubuntu.com/security/notices/USN-8917-1, https://ubuntu.com/security/notices/USN-8918-1, https://ubuntu.com/security/notices/USN-8963-1, https://ubuntu.com/security/notices/USN-9003-1

    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-2026-64534 | CVE-DB