CVE-2026-43040

Description

In the Linux kernel, the following vulnerability has been resolved: net: ipv6: ndisc: fix ndisc_ra_useropt to initialize nduseropt_padX fields to zero to prevent an info-leak When processing Router Advertisements with user options the kernel builds an RTM_NEWNDUSEROPT netlink message. The nduseroptmsg struct has three padding fields that are never zeroed and can leak kernel data The fix is simple, just zeroes the padding fields.

CVSS v3.1 Score

7.1

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.03%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-909 CWE-909

Affected Products

Vendor	Product	Versions
linux	linux_kernel	2.6.24 — 5.10.253
linux	linux_kernel	5.11 — 5.15.203
linux	linux_kernel	5.16 — 6.1.168
linux	linux_kernel	6.2 — 6.6.134
linux	linux_kernel	6.7 — 6.12.81
linux	linux_kernel	6.13 — 6.18.22
linux	linux_kernel	6.19 — 6.19.12
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/11d7fe97421cfc81549940c20ed5ac9472d6db05 https://git.kernel.org/stable/c/1da9023f6b071a38e5430ffbce4b70b2b1ac4f9c https://git.kernel.org/stable/c/2fe4d0ba690a69ad6ae9f7ab9bdc96e02610b648 https://git.kernel.org/stable/c/4f810c686fde509d1cdaa706322d9d2531f8f1a4 https://git.kernel.org/stable/c/7f56d87e527bb5a13c3e8b0d5840cb6332822f6d https://git.kernel.org/stable/c/ae05340ccaa9d347fe85415609e075545bec589f https://git.kernel.org/stable/c/b485eef3d97b7aae55ce669b6de555ec81f3d21c https://git.kernel.org/stable/c/ef3645606e4a635d5062a492f22b7f490852ee67

Frequently Asked Questions

What is CVE-2026-43040? +

In the Linux kernel, the following vulnerability has been resolved: net: ipv6: ndisc: fix ndisc_ra_useropt to initialize nduseropt_padX fields to zero to prevent an info-leak When processing Router Advertisements with user options the kernel builds an RTM_NEWNDUSEROPT netlink message. The nduseroptmsg struct has three padding fields that are never zeroed and can leak kernel data The fix is simple, just zeroes the padding fields. It has a CVSS v3.1 base score of 7.1 (HIGH).

How severe is CVE-2026-43040? +

CVE-2026-43040 has a CVSS v3.1 score of 7.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-43040? +

CVE-2026-43040 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-43040? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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