CyberSecBulletin
CVE-2026-64039NVD status: Analyzed

Linux: Incorrect Calculation of Buffer Size

Published Updated By the CyberSecBulletin desk

CVE-2026-64039 is a high-severity incorrect calculation of buffer size vulnerability in Linux, with a CVSS 3.1 base score of 7.7 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, without any action from a user. The record lists versions 8fb070cf95847b29ef6cb15ec2c0de2bf4704676, cecd34e046121d788a70b5c8b4f8a88916637953, 070e40acc59ef7bedba0314f59971ba87fcc8ab0 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 0.18% 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 8fb070cf95847b29ef6cb15ec2c0de2bf4704676 or cecd34e046121d788a70b5c8b4f8a88916637953 or 070e40acc59ef7bedba0314f59971ba87fcc8ab0 or 1ef79be774706dddcfcace0331fa7ff32a73c73e, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.15.209 or 6.1.175 or 6.6.142 or 6.12.92, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux98659487b845c05b6bed85d881713545db674c7c up to, but not including, 8fb070cf95847b29ef6cb15ec2c0de2bf4704676; 98659487b845c05b6bed85d881713545db674c7c up to, but not including, cecd34e046121d788a70b5c8b4f8a88916637953; 98659487b845c05b6bed85d881713545db674c7c up to, but not including, 070e40acc59ef7bedba0314f59971ba87fcc8ab0; 98659487b845c05b6bed85d881713545db674c7c up to, but not including, 1ef79be774706dddcfcace0331fa7ff32a73c73e; 98659487b845c05b6bed85d881713545db674c7c up to, but not including, cdd1aaf0ee962f50810b9aef7928f2313989d55f; 98659487b845c05b6bed85d881713545db674c7c up to, but not including, 0c90ececfad3fc5c4c43a75ece0e2d736ab3def1; 98659487b845c05b6bed85d881713545db674c7c up to, but not including, 76824d2467feb1828b745d6add2541918d7be3da; 5.148fb070cf95847b29ef6cb15ec2c0de2bf4704676, cecd34e046121d788a70b5c8b4f8a88916637953, 070e40acc59ef7bedba0314f59971ba87fcc8ab0, 1ef79be774706dddcfcace0331fa7ff32a73c73e, cdd1aaf0ee962f50810b9aef7928f2313989d55f, 0c90ececfad3fc5c4c43a75ece0e2d736ab3def1
LinuxLinux Kernel5.14 up to, but not including, 5.15.209; 5.16 up to, but not including, 6.1.175; 6.2 up to, but not including, 6.6.142; 6.7 up to, but not including, 6.12.92; 6.13 up to, but not including, 6.18.34; 6.19 up to, but not including, 7.0.11; 7.15.15.209, 6.1.175, 6.6.142, 6.12.92, 6.18.34, 7.0.11

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
NoneNo account or login is needed.
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
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

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

Official description

In the Linux kernel, the following vulnerability has been resolved: drm/msm/snapshot: fix dumping of the unaligned regions The snapshotting code internally aligns data segment to 16 bytes. This works fine for DPU code (where most of the regions are aligned), but fails for snapshotting of the DSI data (because DSI data region is shifted by 4 bytes). Fix the code by removing length alignment and by accurately printing last registers in the region. While reworking the code also fix the 16x memory overallocation in msm_disp_state_dump_regs(). Patchwork: https://patchwork.freedesktop.org/patch/725449/

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

The underlying weakness: Incorrect Calculation of Buffer Size

The product does not correctly calculate the size to be used when allocating a buffer.

How developers prevent this class of flaw

  • When allocating a buffer for the purpose of transforming, converting, or encoding an input, allocate enough memory to handle the largest possible encoding. For example, in a routine that converts & characters to & for HTML entity encoding, the output buffer needs to be at least 5 times as large as the input buffer.
  • Understand the programming language's underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, not-a-number calculations, and how the language handles numbers that are too large or too small for its underlying representation. Also be careful to account for 32-bit, 64-bit, and other potential differences that may affect the numeric representation.
  • Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range.

More Incorrect Calculation of Buffer Size vulnerabilities (CWE-131)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Recent Incorrect Calculation of Buffer Size vulnerabilities

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