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Linux KernelOperating system · Linux

CVE-2025-37891

HIGH · 7.8 CVSS v3.1 Published 2025-05-19
Fix available
A fix is available. Upgrade to 6.6.90 / 6.12.28 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: ALSA: ump: Fix buffer overflow at UMP SysEx message conversion The conversion function from MIDI 1.0 to UMP packet contains an internal buffer to keep the incoming MIDI bytes, and its size is 4, as it was supposed to be the max size for a MIDI1 UMP packet data. However, the implementation overlooked that SysEx is handled in a different format, and it can be up to 6 bytes, as found in do_convert_to_ump(). It leads eventually to a buffer overflow, and may corrupt the memory when a longer SysEx message is received. The fix is simply to extend the buffer size to 6 to fit with the SysEx UMP message.

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-120

A fixed-size buffer is filled without checking the length of the incoming data, so it overflows into neighbouring memory. This is the classic overflow attackers use to overwrite return addresses and hijack execution. The fix is strict length checks and safe, bounded string and memory functions.

General guidance for the classic buffer overflow 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:>= 6.5, < 6.6.90>= 6.7, < 6.12.28>= 6.13, < 6.14.6= 6.15

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 6.6.90 / 6.12.28 / 6.14.6 or later
Fixed in 6.6.906.12.286.14.6
Vendor patch git.kernel.org →
Recommended fix High confidence

6.6.90 (for 6.5.x-6.6.x), 6.12.28 (for 6.7.x-6.12.x), or 6.14.6 (for 6.13.x-6.15.x)

  1. Identify the current running kernel version using 'uname -r' or 'cat /proc/version'
  2. Determine which kernel branch your version falls into based on affected versions: >= 6.5 to < 6.6.90, >= 6.7 to < 6.12.28, >= 6.13 to < 6.14.6, or = 6.15
  3. Upgrade to the appropriate fixed kernel release: 6.6.90 for 6.5.x-6.6.x users, 6.12.28 for 6.7.x-6.12.x users, 6.14.6 for 6.13.x-6.14.x users, or 6.14.6 or later for 6.15.x users
  4. On Debian/Ubuntu: 'sudo apt-get update && sudo apt-get linux-image-$(uname -r)' or install from official kernel.org packages
  5. On RHEL/CentOS: 'sudo yum update kernel' or 'sudo dnf update kernel'
  6. On Alpine: 'apk update && apk add linux-lts' or use 'apk upgrade'
  7. Reboot the system to load the fixed kernel: 'sudo reboot'
  8. Verify the new kernel version loads correctly and the ALSA ump driver functions without overflow errors
Caveat Kernel upgrades may require rebooting services; ensure compatibility with system hardware and software dependencies 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 $3,200. 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-2025-37891 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
  • No weaponised exploit code, or anything meant to cause harm
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