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Review reviewHigh

CVE-2025-38554

Linux Linux, linux kernel

In the Linux kernel, the following vulnerability has been resolved: mm: fix a UAF when vma->mm is freed after vma->vm_refcnt got dropped By inducing delays in the right places, Jann Horn created a reproducer for a hard to hit UAF issue that became possible after VMAs were allowed to be recycled by adding SLAB_TYPESAFE_BY_RCU to their cache. Race description is borrowed from Jann's discovery report: lock_vma_under_rcu() looks up a VMA locklessly with mas_walk() under rcu_read_lock(). At that point, the VMA may be concurrently freed, and it can be recycled by another process. vma_start_read()...

CVSS
7.8
EPSS
0.16%
5.85% percentile
CISA KEV
Not listed
Published
2025.08.20
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability0.16%
Technical severityCVSS 7.8

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: mm: fix a UAF when vma->mm is freed after vma->vm_refcnt got dropped By inducing delays in the right places, Jann Horn created a reproducer for a hard to hit UAF issue that became possible after VMAs were allowed to be recycled by adding SLAB_TYPESAFE_BY_RCU to their cache. Race description is borrowed from Jann's discovery report: lock_vma_under_rcu() looks up a VMA locklessly with mas_walk() under rcu_read_lock(). At that point, the VMA may be concurrently freed, and it can be recycled by another process. vma_start_read()...

Affected product and versions

Product
Linux Linux, linux kernel
Affected versions
>= 3104138517fc66aad21f4a2487bb572e9fc2e3ec < 6e88fe54721dee17d3496bc998f0c7d243896348, >= 3104138517fc66aad21f4a2487bb572e9fc2e3ec < 1bcd236a2536a451e385f8d6d2bb589689ec812f, >= 3104138517fc66aad21f4a2487bb572e9fc2e3ec < 9bbffee67ffd16360179327b57f3b1245579ef08, >= 6.15, >= 6.15 < 6.15.10, >= 6.16 < 6.16.1
Fixed versions
6.15.10, 6.16.1

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux Linux, linux kernel and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-416
CVE-2025-38554 — Linux Linux, linux kernel | SECUFOCUS NOW