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CVE-2026-31575

5.5 · MEDIUM

In the Linux kernel, the following vulnerability has been resolved: mm/userfaultfd: fix hugetlb fault mutex hash calculation In mfill_atomic_hugetlb(), linear_page_index() is used to calculate th…

Published Apr 24, 2026EPSS 0.16%

Overview

CVE-2026-31575 is a medium-severity vulnerability. It was published on April 24, 2026 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

In the Linux kernel, the following vulnerability has been resolved:

mm/userfaultfd: fix hugetlb fault mutex hash calculation

In mfill_atomic_hugetlb(), linear_page_index() is used to calculate the

page index for hugetlb_fault_mutex_hash(). However, linear_page_index()

returns the index in PAGE_SIZE units, while hugetlb_fault_mutex_hash()

expects the index in huge page units. This mismatch means that different

addresses within the same huge page can produce different hash values,

leading to the use of different mutexes for the same huge page. This can

cause races between faulting threads, which can corrupt the reservation

map and trigger the BUG_ON in resv_map_release().

Fix this by introducing hugetlb_linear_page_index(), which returns the

page index in huge page granularity, and using it in place of

linear_page_index().

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/0217c7fb4de4a40cee667eb21901f3204effe5acRefgit.kernel.org/stable/c/08282b1bf74c69fc8ecd25493e7fdb5460f01290Refgit.kernel.org/stable/c/574501ede47ac439afd67ba9812bc66722d500baRefgit.kernel.org/stable/c/5a525c43baaba0bf3063f86996ca3623b71e4172Refgit.kernel.org/stable/c/f4689fc089765d36c026063fb22d23533e883eb6

How CyberStrike helps

Frequently asked questions

What is CVE-2026-31575?

CVE-2026-31575 is a medium-severity vulnerability. It was published on April 24, 2026 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2026-31575?

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-31575?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-31575?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-31575 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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