CyberSecBulletin
CVE-2025-37891NVD status: Modified

Linux: Buffer Copy without Checking Size of Input

Published Updated By the CyberSecBulletin desk

CVE-2025-37891 is a high-severity buffer copy without checking size of input vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions ce4f77bef276e7d2eb7ab03a5d08bcbaa40710ec, 226beac5605afbb33f8782148d188b64396145a4, 42ef48dd4ebb082a1a90b5c3feeda2e68a9e32fe as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.24% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to ce4f77bef276e7d2eb7ab03a5d08bcbaa40710ec or 226beac5605afbb33f8782148d188b64396145a4 or 42ef48dd4ebb082a1a90b5c3feeda2e68a9e32fe or 56f1f30e6795b890463d9b20b11e576adf5a2f77, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.6.90 or 6.12.28 or 6.14.6, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux0b5288f5fe63eab687c14e5940b9e0d532b129f2 up to, but not including, ce4f77bef276e7d2eb7ab03a5d08bcbaa40710ec; 0b5288f5fe63eab687c14e5940b9e0d532b129f2 up to, but not including, 226beac5605afbb33f8782148d188b64396145a4; 0b5288f5fe63eab687c14e5940b9e0d532b129f2 up to, but not including, 42ef48dd4ebb082a1a90b5c3feeda2e68a9e32fe; 0b5288f5fe63eab687c14e5940b9e0d532b129f2 up to, but not including, 56f1f30e6795b890463d9b20b11e576adf5a2f77; 6.5ce4f77bef276e7d2eb7ab03a5d08bcbaa40710ec, 226beac5605afbb33f8782148d188b64396145a4, 42ef48dd4ebb082a1a90b5c3feeda2e68a9e32fe, 56f1f30e6795b890463d9b20b11e576adf5a2f77
LinuxLinux Kernel6.5 up to, but not including, 6.6.90; 6.7 up to, but not including, 6.12.28; 6.13 up to, but not including, 6.14.6; 6.156.6.90, 6.12.28, 6.14.6

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighCNA
CVSS 3.17.8HighNVD

Official description

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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Buffer Copy without Checking Size of Input

The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Buffer Copy without Checking Size of Input vulnerabilities (CWE-120)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Buffer Copy without Checking Size of Input vulnerabilities

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