CyberSecBulletin
CVE-2026-64402NVD status: Analyzed

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-64402 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 38dbc8db8341ccdf8e1e1a067453d33ad751864b, 4c5a0a946373da99a80398289b28845b5ae40cd1, 661a019ac0413ecec9e5d1dfcc12fbca8e78d5fb 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 38dbc8db8341ccdf8e1e1a067453d33ad751864b or 4c5a0a946373da99a80398289b28845b5ae40cd1 or 661a019ac0413ecec9e5d1dfcc12fbca8e78d5fb or daf6246ab988fc8bdc82ad7c8d0b1c182d11b15f, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.6.145 or 6.12.96 or 6.18.39 or 7.1.4, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux06f5c2926aaa0fba7f99678da6ef77cbbbda1441 up to, but not including, 38dbc8db8341ccdf8e1e1a067453d33ad751864b; 06f5c2926aaa0fba7f99678da6ef77cbbbda1441 up to, but not including, 4c5a0a946373da99a80398289b28845b5ae40cd1; 06f5c2926aaa0fba7f99678da6ef77cbbbda1441 up to, but not including, 661a019ac0413ecec9e5d1dfcc12fbca8e78d5fb; 06f5c2926aaa0fba7f99678da6ef77cbbbda1441 up to, but not including, daf6246ab988fc8bdc82ad7c8d0b1c182d11b15f; 06f5c2926aaa0fba7f99678da6ef77cbbbda1441 up to, but not including, 98495b5a4d77dd22e106f462b76e1093a55b29a7; 6.338dbc8db8341ccdf8e1e1a067453d33ad751864b, 4c5a0a946373da99a80398289b28845b5ae40cd1, 661a019ac0413ecec9e5d1dfcc12fbca8e78d5fb, daf6246ab988fc8bdc82ad7c8d0b1c182d11b15f, 98495b5a4d77dd22e106f462b76e1093a55b29a7
LinuxLinux Kernel6.3 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, 7.1.46.6.145, 6.12.96, 6.18.39, 7.1.4

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 CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: coresight: ultrasoc-smb: Fix OOB write in smb_sync_perf_buffer() When the SMB sink is used as a perf AUX sink, smb_update_buffer() calls smb_sync_perf_buffer() to copy hardware trace data into the perf AUX ring buffer pages. It derives pg_idx = head >> PAGE_SHIFT from @head, which is handle->head, and indexes dst_pages[pg_idx]. The pg_idx %= nr_pages normalization is only applied after the first loop iteration. This leaves the initial page index underived from the buffer size, which can result in an out-of-bounds write past dst_pages[] when head exceeds the AUX buffer size. Normalize head modulo the AUX buffer size before deriving the page index and offset, mirroring tmc_etr_sync_perf_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. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Write vulnerabilities

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