CVE-2026-80727
Received Received - Intake

Linux kernel MCE CMCI timer initialization race condition

Publication date: 2026-09-03

Last updated on: 2026-09-03

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: x86/mce: Set up the polling timer before CMCI discovery I hit the following on one of my machines: mce: CPU0 BANK15 CMCI inherited storm ------------[ cut here ]------------ ODEBUG: assert_init not available (active state 0) object: (____ptrval____) object type: timer_list hint: 0x0 WARNING: lib/debugobjects.c:632 at debug_object_assert_init+0x178/0x230, CPU#0: swapper/0/0 CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 7.2.0-rc5 #3 PREEMPTLAZY RIP: 0010:debug_object_assert_init+0x18f/0x230 Call Trace: <TASK> __mod_timer mce_timer_kick cmci_discover intel_init_cmci mce_intel_feature_init mcheck_cpu_init identify_cpu identify_boot_cpu arch_cpu_finalize_init start_kernel A second splat follows right after, from timer_setup() finding that same timer already queued: ODEBUG: init active (active state 0) object: (____ptrval____) object type: timer_list hint: stub_timer+0x0/0x10 This is happening because CMCI storm detection is trying to modify the timer before latter was properly set up. Set up the timer first. __mcheck_cpu_setup_timer() only calls timer_setup(), and depends on neither the generic nor the vendor init. [ bp: Massage commit message. ]

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Meta Information

Published
2026-09-03
Last Modified
2026-09-03
Generated
2026-09-03
AI Q&A
2026-09-03
EPSS Evaluated
N/A
NVD
CVE-2026-80727
EUVD
EUVD-2026-70331

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel 7.2.0-rc5

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a race condition where the CMCI storm detection mechanism attempts to modify a timer before it is properly initialized. This leads to kernel warnings and potential system instability due to improper timer handling during CPU initialization.

Detection Guidance

This vulnerability manifests as a kernel error related to Machine Check Exception (MCE) timer and CMCI storm detection. Check system logs for messages like 'mce: CPU BANK CMCI inherited storm' or 'ODEBUG: assert_init not available' using commands like 'dmesg | grep mce' or 'journalctl -k | grep mce'.

Impact Analysis

This vulnerability may cause kernel warnings, system instability, or crashes during system boot or CPU initialization. It could lead to unexpected reboots or degraded performance on affected machines.

Mitigation Strategies

Apply the Linux kernel patch that resolves this issue. Update to a kernel version that includes the fix for 'x86/mce: Set up the polling timer before CMCI discovery'. Monitor system logs for MCE-related errors after applying the update.

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