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CVE-2025-38242

7.8 · HIGH

In the Linux kernel, the following vulnerability has been resolved: mm: userfaultfd: fix race of userfaultfd_move and swap cache This commit fixes two kinds of races, they may have different resu…

Published Jul 9, 2025CWE-362EPSS 0.13%

Overview

CVE-2025-38242 is a high-severity vulnerability. It was published on July 9, 2025 and has a CVSS 3.1 base score of 7.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. 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 race of userfaultfd_move and swap cache

This commit fixes two kinds of races, they may have different results:

Barry reported a BUG_ON in commit c50f8e6053b0, we may see the same

BUG_ON if the filemap lookup returned NULL and folio is added to swap

cache after that.

If another kind of race is triggered (folio changed after lookup) we

may see RSS counter is corrupted:

[ 406.893936] BUG: Bad rss-counter state mm:ffff0000c5a9ddc0

type:MM_ANONPAGES val:-1

[ 406.894071] BUG: Bad rss-counter state mm:ffff0000c5a9ddc0

type:MM_SHMEMPAGES val:1

Because the folio is being accounted to the wrong VMA.

I'm not sure if there will be any data corruption though, seems no.

The issues above are critical already.

On seeing a swap entry PTE, userfaultfd_move does a lockless swap cache

lookup, and tries to move the found folio to the faulting vma. Currently,

it relies on checking the PTE value to ensure th

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/0ea148a799198518d8ebab63ddd0bb6114a103bcRefgit.kernel.org/stable/c/4c443046d8c9ed8724a4f4c3c2457d3ac8814b2fRefgit.kernel.org/stable/c/db2ca8074955ca64187a4fb596dd290b9c446cd3

How CyberStrike helps

Frequently asked questions

What is CVE-2025-38242?

CVE-2025-38242 is a high-severity vulnerability. It was published on July 9, 2025 and has a CVSS 3.1 base score of 7.8 (HIGH).

How severe is CVE-2025-38242?

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2025-38242?

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-2025-38242?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-38242 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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