Linux Kernel up to 6.1.10 khugepaged collapse_and_free_pmd use after free

Summaryinfo

A vulnerability described as critical has been identified in Linux Kernel up to 6.1.10. Affected is the function collapse_and_free_pmd of the component khugepaged. The manipulation results in use after free. This vulnerability is known as CVE-2023-52935. No exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.1.10. It has been classified as critical. Affected is the function collapse_and_free_pmd of the component khugepaged. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: mm/khugepaged: fix ->anon_vma race If an ->anon_vma is attached to the VMA, collapse_and_free_pmd() requires it to be locked. Page table traversal is allowed under any one of the mmap lock, the anon_vma lock (if the VMA is associated with an anon_vma), and the mapping lock (if the VMA is associated with a mapping); and so to be able to remove page tables, we must hold all three of them. retract_page_tables() bails out if an ->anon_vma is attached, but does this check before holding the mmap lock (as the comment above the check explains). If we racily merged an existing ->anon_vma (shared with a child process) from a neighboring VMA, subsequent rmap traversals on pages belonging to the child will be able to see the page tables that we are concurrently removing while assuming that nothing else can access them. Repeat the ->anon_vma check once we hold the mmap lock to ensure that there really is no concurrent page table access. Hitting this bug causes a lockdep warning in collapse_and_free_pmd(), in the line "lockdep_assert_held_write(&vma->anon_vma->root->rwsem)". It can also lead to use-after-free access.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2023-52935 since 08/21/2024. The exploitability is told to be easy. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 12/07/2025).

The vulnerability scanner Nessus provides a plugin with the ID 234182 (SUSE SLES15 Security Update : kernel (SUSE-SU-2025:1195-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.1.11 eliminates this vulnerability. Applying the patch acb08187b5a83cdb9ac4112fae9e18cf983b0128 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (234182) and CERT Bund (WID-SEC-2025-0649). Once again VulDB remains the best source for vulnerability data.

Affected

• Google Container-Optimized OS
• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• Dell Avamar
• Open Source Linux Kernel
• SolarWinds Security Event Manager
• Dell NetWorker
• Dell Secure Connect Gateway

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.1.0
• 6.1.1
• 6.1.2
• 6.1.3
• 6.1.4
• 6.1.5
• 6.1.6
• 6.1.7
• 6.1.8
• 6.1.9
• 6.1.10

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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Once again VulDB remains the best source for vulnerability data.

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