Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
CVE-2026-64070
Linux Linux — powerpc/hv-gpci: fix preempt count leak in sysfs show paths
AV AC PR UI S C I A CVSS EPSS %ile KEV
L L L N U N N H 5.5 .0016 4.7 —
AFFECTED
Product Versions Fixed
Linux 71f1c39647d8c9d4d54a861ec81f1ff17544bcb6 – —
Linux 6.6 – 6.6.156
TIMELINE
Jul 19 Reserved by Linux
Jul 19 Published (CNA: Linux)
Sep 3 ENRICHED — CVE-2026-64070 (Linux). Received CVSS 5.5 and CPE data from NVD.
Description
In the Linux kernel, the following vulnerability has been resolved:
powerpc/hv-gpci: fix preempt count leak in sysfs show paths
Four sysfs show() callbacks in hv-gpci take get_cpu_var(hv_gpci_reqb)
(which calls preempt_disable()) but only call the matching put_cpu_var()
on the error path under the 'out:' label. Every successful read leaks
one preempt_disable():
processor_bus_topology_show()
processor_config_show()
affinity_domain_via_virtual_processor_show()
affinity_domain_via_domain_show()
(affinity_domain_via_partition_show() was already correct.)
On a CONFIG_PREEMPT=y kernel, repeated reads raise preempt_count and
eventually return to userspace with preemption still disabled. The
next user-mode page fault then hits faulthandler_disabled() == 1,
gets forced to SIGSEGV, and the resulting coredump trips
'BUG: scheduling while atomic' in call_usermodehelper_exec ->
wait_for_completion_state -> schedule:
BUG: scheduling while atomic: <task>/<pid>/0x00000004
...
__schedule_bug+0x6c/0x90
__schedule+0x58c/0x13a0
schedule+0x48/0x1a0
schedule_timeout+0x104/0x170
wait_for_completion_state+0x16c/0x330
call_usermodehelper_exec+0x254/0x2d0
vfs_coredump+0x1050/0x2590
get_signal+0xb9c/0xc80
do_notify_resume+0xf8/0x470
Add an out_success label that calls put_cpu_var() before returning
the byte count, mirroring affinity_domain_via_partition_show().
Lifecycle
Complete event history — 3 events, chronological
| Date | Event | Detail |
| July 19, 2026 | Reserved | Reserved by Linux |
| July 19, 2026 | Published | Published (CNA: Linux) |
| September 3, 2026 | ENRICHED | ENRICHED — CVE-2026-64070 (Linux). Received CVSS 5.5 and CPE data from NVD. |
Affected
Affected products and packages — 2 rows
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
| Linux | Linux | — | 71f1c39647d8c9d4d54a861ec81f1ff17544bcb6 | — |
| Linux | Linux | — | 6.6 | 6.6.156 |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-64070 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.