CyberSecBulletin
CVE-2026-43093NVD status: Modified

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-43093 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 5f123bc278bf4e3283d8606321bebbfd299f4384, 1a6051cd7e3e4c54ff3854a43b638b9292af5e67, 8769708add9eadeea8041a9761771bb715a87104 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 0.14% 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 5f123bc278bf4e3283d8606321bebbfd299f4384 or 1a6051cd7e3e4c54ff3854a43b638b9292af5e67 or 8769708add9eadeea8041a9761771bb715a87104 or a03975beb9f6af0d8ac051e30b2abeabe618414f, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 4.20 or 5.5 or 5.7 or 6.6.136, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux99e3a236dd43d06c65af0a2ef9cb44306aef6e02 up to, but not including, 5f123bc278bf4e3283d8606321bebbfd299f4384; 99e3a236dd43d06c65af0a2ef9cb44306aef6e02 up to, but not including, 1a6051cd7e3e4c54ff3854a43b638b9292af5e67; 99e3a236dd43d06c65af0a2ef9cb44306aef6e02 up to, but not including, 8769708add9eadeea8041a9761771bb715a87104; 99e3a236dd43d06c65af0a2ef9cb44306aef6e02 up to, but not including, a03975beb9f6af0d8ac051e30b2abeabe618414f; 99e3a236dd43d06c65af0a2ef9cb44306aef6e02 up to, but not including, 0ec4d3f6e6934deb843b561ae048cd17218e5ad1; 99e3a236dd43d06c65af0a2ef9cb44306aef6e02 up to, but not including, 9ea6ba4f3195dcba6e8b3e7b2e748593b7cafb12; 99e3a236dd43d06c65af0a2ef9cb44306aef6e02 up to, but not including, 6523bc1b40e69301f24c14338b762af4739d6d39; 99e3a236dd43d06c65af0a2ef9cb44306aef6e02 up to, but not including, a315e022a72d95ef5f1d4e58e903cb492b0ad931; and 7 more ranges5f123bc278bf4e3283d8606321bebbfd299f4384, 1a6051cd7e3e4c54ff3854a43b638b9292af5e67, 8769708add9eadeea8041a9761771bb715a87104, a03975beb9f6af0d8ac051e30b2abeabe618414f, 0ec4d3f6e6934deb843b561ae048cd17218e5ad1, 9ea6ba4f3195dcba6e8b3e7b2e748593b7cafb12
SiemensSIMATIC S7-1500 TM MFP - GNU/Linux subsystemall versionsNot stated
LinuxLinux Kernel4.19.118 up to, but not including, 4.20; 5.4.35 up to, but not including, 5.5; 5.6.7 up to, but not including, 5.7; 5.7.1 up to, but not including, 6.6.136; 6.7 up to, but not including, 6.12.83; 6.13 up to, but not including, 6.18.24; 6.19 up to, but not including, 6.19.14; 5.7; and 1 more ranges4.20, 5.5, 5.7, 6.6.136, 6.12.83, 6.18.24

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: xsk: tighten UMEM headroom validation to account for tailroom and min frame The current headroom validation in xdp_umem_reg() could leave us with insufficient space dedicated to even receive minimum-sized ethernet frame. Furthermore if multi-buffer would come to play then skb_shared_info stored at the end of XSK frame would be corrupted. HW typically works with 128-aligned sizes so let us provide this value as bare minimum. Multi-buffer setting is known later in the configuration process so besides accounting for 128 bytes, let us also take care of tailroom space upfront.

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: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Write vulnerabilities

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