# CVE-2026-64250: LoongArch: Report dying CPU to RCU in stop_this_cpu() CVE-2026-64250 is fixed in 38 products on 1 platform, first by ALAS2023-2026-1969, released July 20, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-64250 - Priority: Routine - CVSS: 5.5 (Moderate) - EPSS: 0.0016 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Jul 20, 2026 - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64250 ## Description 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. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool6.12 amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | bpftool6.12-debuginfo amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | bpftool6.18 amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | bpftool6.18-debuginfo amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | kernel-livepatch-6.12.95-124.187 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | kernel-livepatch-6.18.38-73.137 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | kernel6.12 amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | kernel6.12-debuginfo amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | kernel6.12-debuginfo-common-aarch64 amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | kernel6.12-debuginfo-common-x86_64 amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | kernel6.12-devel amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | kernel6.12-headers amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | kernel6.12-modules-extra amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | kernel6.12-modules-extra-common amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | kernel6.12-tools amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | kernel6.12-tools-debuginfo amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | kernel6.12-tools-devel amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | kernel6.18 amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | kernel6.18-debuginfo amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | kernel6.18-debuginfo-common-aarch64 amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | kernel6.18-debuginfo-common-x86_64 amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | kernel6.18-devel amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | kernel6.18-headers amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | kernel6.18-modules-extra amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | kernel6.18-modules-extra-common amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | kernel6.18-tools amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | kernel6.18-tools-debuginfo amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | kernel6.18-tools-devel amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | linux Debian 12.15 (bookworm) | 6.1.180-1 | [DEBIAN-CVE-2026-64250](https://patchblox.com/security/data/fix/linux/debian-cve-2026-64250.md) | Jul 25, 2026 | | Linux | linux Debian 13.5 (trixie) | 6.12.95-1 | [DEBIAN-CVE-2026-64250](https://patchblox.com/security/data/fix/linux/debian-cve-2026-64250.md) | Jul 25, 2026 | | Linux | linux Debian 14 | 7.1.3-1 | [DEBIAN-CVE-2026-64250](https://patchblox.com/security/data/fix/linux/debian-cve-2026-64250.md) | Jul 25, 2026 | | Linux | microvm-kernel6.18 amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | perf6.12 amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | perf6.12-debuginfo amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | perf6.18 amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | perf6.18-debuginfo amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | python3-perf6.12 amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | python3-perf6.12-debuginfo amzn 2023 | 1:6.12.95-124.187.amzn2023 | [ALAS2023-2026-2014](https://patchblox.com/security/data/fix/linux/alas2023-2026-2014.md) | Aug 3, 2026 | | Linux | python3-perf6.18 amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | | Linux | python3-perf6.18-debuginfo amzn 2023 | 1:6.18.38-73.137.amzn2023 | [ALAS2023-2026-1969](https://patchblox.com/security/data/fix/linux/alas2023-2026-1969.md) | Jul 20, 2026 | --- Data as of 2026-11-10T01:44:33Z UTC. 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