CVE-2026-97943
Received Received - Intake

Use-After-Free in Linux Kernel Page Attribute Table Handling

Publication date: 2026-09-25

Last updated on: 2026-09-25

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: x86/mm/pat: Acquire init_mm write lock on collapse to avoid UAF x86 implements page attribute modification using its Change Page Attributes (CPA) mechanism. This tracks properties of ranges such as cache mode through x86 page attributes, and as part of that logic manipulates kernel page tables. Since commit: 41d88484c71c ("x86/mm/pat: restore large ROX pages after fragmentation") ranges of kernel page table entries can be collapsed into huge page table entries as part of this logic. As part of this collapse, it frees the page tables which the collapsed entries previously pointed to, and it does so without any relevant locks being held to preclude concurrent kernel page table walkers. The only way this code can be reached is if CPA_COLLAPSE is specified, and this is only set in set_memory_rox() via: set_memory_rox() -> change_page_attr_set_clr() -> cpa_flush() -> cpa_collapse_large_pages() Notable users of this are execmem and BPF when manipulating executable mappings. However, this is problematic for ptdump as it walks ranges it does not own and thus runs the risk of a use-after-free on page tables freed underneath it. In addition, concurrent CPA collapse operations are possible which can also cause races. Resolve the issue by acquiring the mmap write lock on init_mm across the whole operation. It is safe to acquire a sleeping lock as all the callers invoke set_memory_rox() from process context and in any case, change_page_attr_set_clr() calls vm_unmap_alias() which ultimately takes a mutex, disallowing atomic context here.

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Meta Information

Published
2026-09-25
Last Modified
2026-09-25
Generated
2026-09-25
AI Q&A
2026-09-25
EPSS Evaluated
N/A
NVD
CVE-2026-97943
EUVD
EUVD-2026-86797

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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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 use-after-free (UAF) issue in the x86 page attribute modification mechanism. When page tables are collapsed into huge pages, they are freed without proper locking, allowing concurrent kernel page table walkers to access freed memory. This can lead to crashes or privilege escalation.

Detection Guidance

This vulnerability is specific to the Linux kernel's page attribute table (PAT) mechanism and requires kernel-level detection. Monitor kernel logs for page table corruption or use-after-free errors. Check for crashes in processes using execmem or BPF, as they may trigger the vulnerable code path. No direct commands are provided in the context.

Impact Analysis

If exploited, this vulnerability could allow an attacker to cause system crashes, corrupt memory, or escalate privileges. It primarily affects systems using BPF or execmem features that manipulate executable mappings, potentially leading to arbitrary code execution.

Mitigation Strategies

Apply the latest kernel patches from your Linux distribution to resolve the issue. Avoid using CPA_COLLAPSE operations if possible. Monitor for kernel crashes or page table corruption. Restrict access to BPF and execmem operations until patched.

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