CVE-2026-43089

In the Linux kernel, the following vulnerability has been resolved: xfrm_user: fix info leak in build_mapping() struct xfrm_usersa_id has a one-byte padding hole after the proto field, which ends up never getting set to zero before copying out to userspace. Fix that up by zeroing out the whole structure before setting individual variables.

What this means for your business

It affects Linux Kernel. It matters if your company, or a supplier that handles your data, runs it.
An attacker can use it only with access to the machine itself, with an ordinary user login, and without anyone at your company clicking anything.
FIRST's prediction model gives it a 0.1% chance of attack attempts being seen in the next 30 days, ranking above 2% of all known flaws.

What to do

1Check whether your company or your suppliers run Linux Kernel, and which version. The affected versions are listed further down this page.
2If you do, apply the vendor's fix. A patch or vendor advisory has been published.

Not sure if your company is exposed?

Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.

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Scoring

CVSS: 5.5 (v3.1)
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-401
Assigned by: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Dates

Published: 2026-05-06
Last modified: 2026-09-08
Sources: NVD

Affected products

Linux Linux Kernel2.6.29.1 - 6.6.136, 6.7 - 6.12.83, 6.13 - 6.18.24, 6.19 - 6.19.14, 7.0

As listed in the NVD configuration data. Not a statement about your estate.