What’s Vulnerable › Vulnerabilities

CVE-2025-38686: userfaultfd: fix a crash in UFFDIO_MOVE when PMD is a migration entry

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-09-04 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: userfaultfd: fix a crash in UFFDIO_MOVE when PMD is a migration entry When UFFDIO_MOVE encounters a migration PMD entry, it proceeds with obtaining a folio and accessing it even though the entry is swp_entry_t. Add the missing check and let split_huge_pmd() handle migration entries. While at it also remove unnecessary folio check. [surenb@google.com: remove extra folio check, per David]

Affected products

• Linux kernel: from 6.8 before 6.12.43; from 6.13 before 6.15.11; from 6.16 before 6.16.2; 6.17-rc1 — fixed in 6.12.43, 6.15.11, 6.16.2

How to fix

Upgrade to a fixed version: Linux kernel 6.12.43, 6.15.11, 6.16.2. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/1202abad7a7ccd28c426d2844771a387b07629a4
• https://git.kernel.org/stable/c/7f1101a0a181243ad587ececdffc4845f035549f
• https://git.kernel.org/stable/c/aba6faec0103ed8f169be8dce2ead41fcb689446
• https://git.kernel.org/stable/c/bb81c18dbd42650c844e160cafa7cbb20243a96a

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