CyberSecBulletin
CVE-2026-64381NVD status: Analyzed

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-64381 is a high-severity out-of-bounds write 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 94e4f672db029414b9888b5137a7559f1febf2d8, 68fc0b6cc03ca58060c0f36454e169f5fe258974, 07e0ab81df1790afa35732a4e8e07ff831b29008 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 0.13% 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 94e4f672db029414b9888b5137a7559f1febf2d8 or 68fc0b6cc03ca58060c0f36454e169f5fe258974 or 07e0ab81df1790afa35732a4e8e07ff831b29008 or 9136a08dc29328edd9867f2545e73906ac9df93b, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.261 or 5.15.212 or 6.1.178 or 6.6.145, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxb24df3e30cbf48255db866720fb71f14bf9d2f39 up to, but not including, 94e4f672db029414b9888b5137a7559f1febf2d8; b24df3e30cbf48255db866720fb71f14bf9d2f39 up to, but not including, 68fc0b6cc03ca58060c0f36454e169f5fe258974; b24df3e30cbf48255db866720fb71f14bf9d2f39 up to, but not including, 07e0ab81df1790afa35732a4e8e07ff831b29008; b24df3e30cbf48255db866720fb71f14bf9d2f39 up to, but not including, 9136a08dc29328edd9867f2545e73906ac9df93b; b24df3e30cbf48255db866720fb71f14bf9d2f39 up to, but not including, 67097772df7791c53d608f04bd31c676ccf79b83; b24df3e30cbf48255db866720fb71f14bf9d2f39 up to, but not including, 297243e365fc9fe2f8e9b7dd535a65d922cd108b; b24df3e30cbf48255db866720fb71f14bf9d2f39 up to, but not including, 927d4805aea0a287d36dd4f826ee24d69a2afee3; b24df3e30cbf48255db866720fb71f14bf9d2f39 up to, but not including, 1c6267a1d5cf4c73b656f8181b310cbbb3e4767b; and 1 more ranges94e4f672db029414b9888b5137a7559f1febf2d8, 68fc0b6cc03ca58060c0f36454e169f5fe258974, 07e0ab81df1790afa35732a4e8e07ff831b29008, 9136a08dc29328edd9867f2545e73906ac9df93b, 67097772df7791c53d608f04bd31c676ccf79b83, 297243e365fc9fe2f8e9b7dd535a65d922cd108b
LinuxLinux Kernel4.19 up to, but not including, 5.10.261; 5.11 up to, but not including, 5.15.212; 5.16 up to, but not including, 6.1.178; 6.2 up to, but not including, 6.6.145; 6.7 up to, but not including, 6.12.96; 6.13 up to, but not including, 6.18.39; 6.19 up to, but not including, 7.1.45.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, 6.18.39

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.

Official description

In the Linux kernel, the following vulnerability has been resolved: smb: client: Fix next buffer leak in receive_encrypted_standard() receive_encrypted_standard() allocates next_buffer before checking whether the number of compound PDUs already reached MAX_COMPOUND. If the limit check fails, the function returns immediately and the newly allocated next_buffer is not assigned to server->smallbuf/server->bigbuf, making it leaked. Move the MAX_COMPOUND check before allocating next_buffer.

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

The underlying weakness: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended 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 Out-of-bounds Write vulnerabilities (CWE-787)

Timeline

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

References

Recent Out-of-bounds Write vulnerabilities

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