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Linux KernelOperating system · Linux

CVE-2026-64250

MEDIUM · 5.5 CVSS v3.1 Published 2026-07-24
Fix available
A fix is available. Upgrade to 6.1.178 / 6.6.145 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click 4 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: LoongArch: Report dying CPU to RCU in stop_this_cpu() This is a port of MIPS commit 9f3f3bdc6d9dac1 ("MIPS: smp: report dying CPU to RCU in stop_this_cpu()"). smp_send_stop() parks all secondary CPUs in stop_this_cpu(). And 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. However, since commit 91840be8f710370 ("irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT"), irq_work_sync() calls synchronize_rcu() on architectures without an irq_work self-IPI, i.e. where arch_irq_work_has_interrupt() returns false. Any irq_work_sync() issued in the reboot/shutdown/halt 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 needs some hacks to reproduce, and it was not noticed on LoongArch because arch_irq_work_has_interrupt() usually returns true. 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. LoongArch shuts down all CPUs here without going through the CPU-hotplug mechanism, so this report is not otherwise issued.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 6.1.175, < 6.1.178>= 6.6.142, < 6.6.145>= 6.12.92, < 6.12.95>= 6.18.34, < 6.18.38>= 7.0.11, < 7.1>= 7.1.1, < 7.1.3= 7.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.1.178 / 6.6.145 / 6.12.95 or later
Fixed in 6.1.1786.6.1456.12.95
Recommended fix High confidence

Upgrade to kernel 6.1.178, 6.6.145, 6.12.95, or 6.18.38 (depending on which kernel branch you are on)

  1. Identify the current running kernel version using 'uname -r'
  2. Check if the version falls within any of the affected ranges: 6.1.175-6.1.177, 6.6.142-6.6.144, 6.12.92-6.12.94, or 6.18.34-6.18.37
  3. If affected, upgrade the Linux kernel to the fixed release: 6.1.178, 6.6.145, 6.12.95, or 6.18.38 respectively
  4. After kernel upgrade, reboot the system to load the fixed kernel
  5. Verify the fix is applied by checking the kernel version and confirming the specific commit (which adds rcutree_report_cpu_dead() call in stop_this_cpu for LoongArch) is included
Caveat This is a low-risk fix that only affects LoongArch architecture during shutdown/reboot. Upgrading within the same kernel branch should have minimal breaking changes.

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

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