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Linux KernelOperating system · Linux

CVE-2025-38579

HIGH · 7.8 CVSS v3.1 Published 2025-08-19
Fix available
A fix is available. Upgrade to 5.15.190 / 6.1.148 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: f2fs: fix KMSAN uninit-value in extent_info usage KMSAN reported a use of uninitialized value in `__is_extent_mergeable()` and `__is_back_mergeable()` via the read extent tree path. The root cause is that `get_read_extent_info()` only initializes three fields (`fofs`, `blk`, `len`) of `struct extent_info`, leaving the remaining fields uninitialized. This leads to undefined behavior when those fields are accessed later, especially during extent merging. Fix it by zero-initializing the `extent_info` struct before population.

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
How this class of weakness works · CWE-908

Memory or a resource is used before it has been initialised, so its contents are whatever happened to be there — sometimes leaking earlier data, sometimes values an attacker can influence. Behaviour becomes unpredictable and occasionally exploitable. Remediation is initialising every resource before use and ensuring initialisation happens on all code paths.

General guidance for the use of uninitialized resource class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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:>= 5.15, < 5.15.190>= 5.16, < 6.1.148>= 6.2, < 6.6.102>= 6.7, < 6.12.42>= 6.13, < 6.15.10>= 6.16, < 6.16.1
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 5.15.190 / 6.1.148 / 6.6.102 or later
Fixed in 5.15.1906.1.1486.6.102
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux Kernel 5.15.190, 6.1.148, 6.6.102, or 6.12.42 (or newer stable release); Debian 12 or later

  1. 1. Identify the currently running kernel version using `uname -r`
  2. 2. For RHEL/CentOS and other Enterprise Linux: Update kernel package to version >= 5.15.190, >= 6.1.148, >= 6.6.102, or >= 6.12.42 depending on your base version using `yum update kernel` or `dnf update kernel`
  3. 3. For Ubuntu/Debian: Update kernel package using `apt update && apt install linux-image-<version>` to a version >= 6.12.42
  4. 4. For Debian 11 (Bullseye): Either upgrade to Debian 12 for a newer fixed kernel, or apply the upstream patch from commit 01b6f5955e0008af6bc3a181310d2744bb349800 to the Debian kernel package
  5. 5. Reboot the system to load the fixed kernel using `reboot`
  6. 6. Verify the new kernel version is running using `uname -r` and confirm it is a version listed in step 2 or higher
Caveat Kernel upgrades may require system reboot and could have compatibility implications with custom kernel modules or specific hardware drivers; Debian 11 to 12 upgrade requires thorough testing of applications

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-2025-38579 in production — separate from our analysis above.

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What this is

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  • Version or environment caveats, and links to real fixes
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