In the Linux kernel, the following vulnerability has been resolved: srcu: Don't queue workqueue handlers to never-online CPUs While an srcu_struct structure is in the midst of switching from CPU-0 to all-CPUs state, it can attempt to invoke callbacks for CPUs that have never been online. Worse yet, it can attempt in invoke callbacks for CPUs that never will be online, even including imaginary CPUs not in cpu_possible_mask. This can cause hangs on s390, which is not set up to deal with workqueue handlers being scheduled on such CPUs. This commit therefore causes Tree SRCU to refrain from queueing workqueue handlers on CPUs that have not yet (and might never) come online. Because callbacks are not invoked on CPUs that have not been online, it is an error to invoke call_srcu(), synchronize_srcu(), or synchronize_srcu_expedited() on a CPU that is not yet fully online. However, it turns out to be less code to redirect the callbacks from too-early invocations of call_srcu() than to warn about such invocations. This commit therefore also redirects callbacks queued on not-yet-fully-online CPUs to the boot CPU.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - In the Linux kernel, the following vulnerability has been resolved: srcu: Don't queue workqueue handlers     to never-online CPUs While an srcu_struct structure is in the midst of switching from CPU-0 to all-CPUs     state, it can attempt to invoke callbacks for CPUs that have never been online. Worse yet, it can attempt     in invoke callbacks for CPUs that never will be online, even including imaginary CPUs not in     cpu_possible_mask. This can cause hangs on s390, which is not set up to deal with workqueue handlers being     scheduled on such CPUs. This commit therefore causes Tree SRCU to refrain from queueing workqueue handlers     on CPUs that have not yet (and might never) come online. Because callbacks are not invoked on CPUs that     have not been online, it is an error to invoke call_srcu(), synchronize_srcu(), or     synchronize_srcu_expedited() on a CPU that is not yet fully online. However, it turns out to be less code     to redirect the callbacks from too-early invocations of call_srcu() than to warn about such invocations.
    This commit therefore also redirects callbacks queued on not-yet-fully-online CPUs to the boot CPU.
    (CVE-2026-64211)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
343532	Ubuntu 24.04 LTS / Pro Realtime 24.04 LTS : Linux kernel (GCP) vulnerabilities (USN-8728-1)	Nessus	Ubuntu Local Security Checks	Local	high
340681	Ubuntu 24.04 LTS / 26.04 LTS / Pro Realtime 24.04 LTS : Linux kernel (NVIDIA) vulnerabilities (USN-8663-1)	Nessus	Ubuntu Local Security Checks	Local	high
340045	Ubuntu 26.04 LTS : Linux kernel (NVIDIA BaseOS) vulnerabilities (USN-8664-1)	Nessus	Ubuntu Local Security Checks	Local	high
330163	Linux Distros Unpatched Vulnerability : CVE-2026-64211	Nessus	Misc.	Local	medium

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CVE-2026-64211

medium

Tenable Plugins

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high

medium