CyberSecBulletin
CVE-2026-43166NVD status: Analyzed

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-43166 is a high-severity out-of-bounds write vulnerability in Linux, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists versions 9d5a97bc71ed5783687705c708454c4453aa91d1, d3790f26d38606f020212486359b84632c19d08b, 4a2d046e4b13202a6301a993961f5b30ae4d7119 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 9d5a97bc71ed5783687705c708454c4453aa91d1 or d3790f26d38606f020212486359b84632c19d08b or 4a2d046e4b13202a6301a993961f5b30ae4d7119, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.18.16 or 6.19.6, whichever matches your release line, or a later version.
  3. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux1d191b4ca51d73699cb127386b95ac152af2b930 up to, but not including, 9d5a97bc71ed5783687705c708454c4453aa91d1; 1d191b4ca51d73699cb127386b95ac152af2b930 up to, but not including, d3790f26d38606f020212486359b84632c19d08b; 1d191b4ca51d73699cb127386b95ac152af2b930 up to, but not including, 4a2d046e4b13202a6301a993961f5b30ae4d7119; 6.159d5a97bc71ed5783687705c708454c4453aa91d1, d3790f26d38606f020212486359b84632c19d08b, 4a2d046e4b13202a6301a993961f5b30ae4d7119
LinuxLinux Kernel6.15 up to, but not including, 6.18.16; 6.19 up to, but not including, 6.19.6; 7.06.18.16, 6.19.6

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
NoneNo account or login is needed.
User interaction
RequiredA user must take an action such as opening a file or link.
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:R/S:U/C:H/I:N/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: erofs: fix interlaced plain identification for encoded extents Only plain data whose start position and on-disk physical length are both aligned to the block size should be classified as interlaced plain extents. Otherwise, it must be treated as shifted plain extents. This issue was found by syzbot using a crafted compressed image containing plain extents with unaligned physical lengths, which can cause OOB read in z_erofs_transform_plain().

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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