CVE Catalog

CVE-2026-64229

MediumCVSS 5.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.17%

6th percentile - higher than 6% of all known CVEs

Summary

In the Linux kernel, a vulnerability was found in the TLB invalidation mechanism on x86 architecture. When booting with 'nopcid' (disabling PCID), broadcast TLB invalidation (INVLPGB) can still be used with a non-zero PCID, causing a general protection fault (#GP) and system crash.

Risk Assessment

An attacker can exploit this vulnerability to trigger a kernel panic on systems with AMD processors supporting INVLPGB when booted with 'nopcid'. This leads to denial of service (DoS) and potential system instability.

Recommendation

Immediately update the Linux kernel to a version containing the fix that makes INVLPGB support dependent on PCID being enabled. If an update is not possible, avoid booting the kernel with the 'nopcid' parameter on vulnerable systems.

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: x86/mm: Disable broadcast TLB flush when PCID is disabled Booting with "nopcid" clears X86_FEATURE_PCID and keeps CR4.PCIDE from being set to one. On AMD CPUs that support INVLPGB, broadcast TLB flushing remains enabled. There are two checks that decide whether the global ASID code runs, mm_global_asid() and consider_global_asid(), that key off of the X86_FEATURE_INVLPGB feature. Once an mm becomes active on more than three CPUs, consider_global_asid() assigns it a global ASID, after which flush_tlb_mm_range() takes the broadcast_tlb_flush() path using a non-zero PCID. Issuing an INVLPGB with a non-zero PCID while CR4.PCIDE is not set results in a #GP: Oops: general protection fault, kernel NULL pointer dereference 0x1: 0000 [#1] SMP NOPTI CPU: 158 UID: 0 PID: 3119 Comm: snap Not tainted 7.1.0-rc3 #1 PREEMPT(full) Hardware name: ... RIP: 0010:broadcast_tlb_flush Code: ... 89 da 48 83 c8 07 <0f> 01 fe eb 08 cc cc cc ... Call Trace: <TASK> flush_tlb_mm_range ptep_clear_flush wp_page_copy ? _raw_spin_unlock __handle_mm_fault handle_mm_fault do_user_addr_fault exc_page_fault asm_exc_page_fault All processors that support broadcast TLB invalidation also have PCID support, so it is only the "nopcid" scenario that is of concern. In this situation just disable the broadcast TLB support using the CPUID dependency support by making X86_FEATURE_INVLPGB dependent on X86_FEATURE_PCID. [ bp: Massage commit message. ]

Vulnerability data from NVD (NIST) · CISA KEV · EPSS