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Linux KernelOperating system · Linux

CVE-2025-38257

HIGH · 7.8 CVSS v3.1 Published 2025-07-09
Fix available
A fix is available. Upgrade to 5.15.187 / 6.1.143 or later.
See remediation →
80/100
Remediation priority · High
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: s390/pkey: Prevent overflow in size calculation for memdup_user() Number of apqn target list entries contained in 'nr_apqns' variable is determined by userspace via an ioctl call so the result of the product in calculation of size passed to memdup_user() may overflow. In this case the actual size of the allocated area and the value describing it won't be in sync leading to various types of unpredictable behaviour later. Use a proper memdup_array_user() helper which returns an error if an overflow is detected. Note that it is different from when nr_apqns is initially zero - that case is considered valid and should be handled in subsequent pkey_handler implementations. Found by Linux Verification Center (linuxtesting.org).

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 5.4, < 5.15.187>= 5.16, < 6.1.143>= 6.2, < 6.6.96>= 6.7, < 6.12.36>= 6.13, < 6.15.5= 6.16
Debian LinuxOperating system
Affected:= 11.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.15.187 / 6.1.143 / 6.6.96 or later
Fixed in 5.15.1876.1.1436.6.96
Vendor patch git.kernel.org →
Recommended fix High confidence

Upgrade to Linux kernel 5.15.187+, 6.1.143+, 6.6.96+, or 6.12.36+ (or later stable releases) depending on the currently deployed branch

  1. Identify the current running kernel version using 'uname -r'
  2. Determine which kernel branch is in use (e.g., 5.15.x, 6.1.x, 6.6.x, or 6.7.x-6.12.x)
  3. Upgrade the Linux kernel to a fixed version: for 5.4 to 5.15.x upgrade to 5.15.187 or later; for 5.16 to 6.1.x upgrade to 6.1.143 or later; for 6.2 to 6.6.x upgrade to 6.6.96 or later; for 6.7 to 6.12.x upgrade to 6.12.36 or later
  4. Update the boot loader configuration if necessary (e.g., update-grub for GRUB)
  5. Reboot the system to load the fixed kernel
  6. Verify the kernel version after reboot using 'uname -r' to confirm the fix is applied
Caveat Kernel upgrades may require rebuilding out-of-tree kernel modules; ensure third-party drivers are compatible with the target kernel version before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,950. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-38257 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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