CVE-2026-64248
MIPS: smp: report dying CPU to RCU in stop_this_cpu()
Description
In the Linux kernel, the following vulnerability has been resolved: MIPS: smp: report dying CPU to RCU in stop_this_cpu() smp_send_stop() parks all secondary CPUs in stop_this_cpu(). The function marks the CPU offline for the scheduler via set_cpu_online(false) but never informs RCU, so RCU keeps expecting a quiescent state from CPUs that are now spinning forever with interrupts disabled. As long as nothing waits for an RCU grace period after smp_send_stop() this is harmless, which is why it went unnoticed. Since commit 91840be8f710 ("irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT") however, irq_work_sync() calls synchronize_rcu() on architectures without an irq_work self-IPI, i.e. where arch_irq_work_has_interrupt() returns false. That is the asm-generic default used by MIPS. Any irq_work_sync() issued in the reboot/shutdown path after smp_send_stop() then blocks on a grace period that can never complete, hanging the reboot: WARNING: CPU: 0 PID: 15 at kernel/irq_work.c:144 irq_work_queue_on ... rcu: INFO: rcu_sched detected stalls on CPUs/tasks: rcu: Offline CPU 1 blocking current GP. rcu: Offline CPU 2 blocking current GP. rcu: Offline CPU 3 blocking current GP. This issue was noticed on several Realtek MIPS switch SoCs (MIPS interAptiv) and came up during kernel bump downstream in OpenWrt from 6.18.33 to 6.18.34, after the backport of the patch to the 6.18 stable branch. The patch also has been backported all the way back to 6.1. Call rcutree_report_cpu_dead() once interrupts are disabled, mirroring the generic CPU-hotplug offline path, so RCU stops waiting on the parked CPUs and grace periods can still complete. MIPS shuts down all CPUs here without going through the CPU-hotplug mechanism, so this report is not otherwise issued. Reporting a dying CPU to RCU outside the regular hotplug offline path is not unprecedented: arm64 does the same in cpu_die_early(). There it is an exception for a CPU that was coming online and is aborting bringup, rather than the default shutdown action as on MIPS.
INFO
Published Date :
July 24, 2026, 4:16 p.m.
Last Modified :
July 24, 2026, 4:16 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products
The following products are affected by CVE-2026-64248
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Update the Linux kernel to include the fix.
- Apply the patch to stop RCU waiting on parked CPUs.
- Ensure RCU is notified when CPUs go offline.
- Report dying CPUs to RCU in stop_this_cpu().
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-64248.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-64248 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-64248
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-64248 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-64248 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jul. 24, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '2dc79362302922cb18f35e262712b5e58de65442', 'lessThan': 'f8a1ef884013dc99f712d3eb75624c7cd3fd94f6', 'versionType': 'git'}, {'status': 'affected', 'version': 'eef4f71b46a9929ac33e968538c9dd5d96a02460', 'lessThan': 'e1919d026706544cb6e7251ec06e908edd6f34ee', 'versionType': 'git'}, {'status': 'affected', 'version': '684a78183c54c23e70d1cba320f7fc184604210b', 'lessThan': '6eda71977ee11c222f8ad4cae4d18d50448e56f4', 'versionType': 'git'}, {'status': 'affected', 'version': '18c0456ea2615b1a743a6db739c74411c3b42bc6', 'lessThan': 'f9b57a0015c241274651f4b36627f56b1b5a8651', 'versionType': 'git'}, {'status': 'affected', 'version': '91840be8f710370607f949a627e070896faeddb8', 'lessThan': '9fef09df42df55ab819b285ea892e0fc1b95a9c4', 'versionType': 'git'}, {'status': 'affected', 'version': '91840be8f710370607f949a627e070896faeddb8', 'lessThan': '9f3f3bdc6d9dac1a5a8262ee7ad0f2ff1527a7e7', 'versionType': 'git'}, {'status': 'affected', 'version': '81b582784518196eff1050212a046bc29d3a05dd', 'versionType': 'git'}, {'status': 'affected', 'version': '6.1.175', 'lessThan': '6.1.178', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.6.142', 'lessThan': '6.6.145', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.12.92', 'lessThan': '6.12.95', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.18.34', 'lessThan': '6.18.38', 'versionType': 'semver'}, {'status': 'affected', 'version': '7.0.11', 'lessThan': '7.1', 'versionType': 'semver'}], 'programFiles': ['arch/mips/kernel/smp.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '7.1'}, {'status': 'unaffected', 'version': '0', 'lessThan': '7.1', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.1.178', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.95', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.38', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.3', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['arch/mips/kernel/smp.c'], 'defaultStatus': 'affected'}] Added Description In the Linux kernel, the following vulnerability has been resolved: MIPS: smp: report dying CPU to RCU in stop_this_cpu() smp_send_stop() parks all secondary CPUs in stop_this_cpu(). The function marks the CPU offline for the scheduler via set_cpu_online(false) but never informs RCU, so RCU keeps expecting a quiescent state from CPUs that are now spinning forever with interrupts disabled. As long as nothing waits for an RCU grace period after smp_send_stop() this is harmless, which is why it went unnoticed. Since commit 91840be8f710 ("irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT") however, irq_work_sync() calls synchronize_rcu() on architectures without an irq_work self-IPI, i.e. where arch_irq_work_has_interrupt() returns false. That is the asm-generic default used by MIPS. Any irq_work_sync() issued in the reboot/shutdown path after smp_send_stop() then blocks on a grace period that can never complete, hanging the reboot: WARNING: CPU: 0 PID: 15 at kernel/irq_work.c:144 irq_work_queue_on ... rcu: INFO: rcu_sched detected stalls on CPUs/tasks: rcu: Offline CPU 1 blocking current GP. rcu: Offline CPU 2 blocking current GP. rcu: Offline CPU 3 blocking current GP. This issue was noticed on several Realtek MIPS switch SoCs (MIPS interAptiv) and came up during kernel bump downstream in OpenWrt from 6.18.33 to 6.18.34, after the backport of the patch to the 6.18 stable branch. The patch also has been backported all the way back to 6.1. Call rcutree_report_cpu_dead() once interrupts are disabled, mirroring the generic CPU-hotplug offline path, so RCU stops waiting on the parked CPUs and grace periods can still complete. MIPS shuts down all CPUs here without going through the CPU-hotplug mechanism, so this report is not otherwise issued. Reporting a dying CPU to RCU outside the regular hotplug offline path is not unprecedented: arm64 does the same in cpu_die_early(). There it is an exception for a CPU that was coming online and is aborting bringup, rather than the default shutdown action as on MIPS. Added Reference https://git.kernel.org/stable/c/6eda71977ee11c222f8ad4cae4d18d50448e56f4 Added Reference https://git.kernel.org/stable/c/9f3f3bdc6d9dac1a5a8262ee7ad0f2ff1527a7e7 Added Reference https://git.kernel.org/stable/c/9fef09df42df55ab819b285ea892e0fc1b95a9c4 Added Reference https://git.kernel.org/stable/c/e1919d026706544cb6e7251ec06e908edd6f34ee Added Reference https://git.kernel.org/stable/c/f8a1ef884013dc99f712d3eb75624c7cd3fd94f6 Added Reference https://git.kernel.org/stable/c/f9b57a0015c241274651f4b36627f56b1b5a8651