Linux Kernel up to 6.19.11 mpls platform_label out-of-bounds

Summaryinfo

A vulnerability marked as critical has been reported in Linux Kernel up to 6.19.11. The affected element is the function platform_label of the component mpls. The manipulation leads to out-of-bounds. This vulnerability is uniquely identified as CVE-2026-43042. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.19.11 and classified as problematic. This issue affects the function platform_label of the component mpls. The manipulation with an unknown input leads to a out-of-bounds vulnerability. Using CWE to declare the problem leads to CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: mpls: add seqcount to protect the platform_label{,s} pair The RCU-protected codepaths (mpls_forward, mpls_dump_routes) can have an inconsistent view of platform_labels vs platform_label in case of a concurrent resize (resize_platform_label_table, under platform_mutex). This can lead to OOB accesses. This patch adds a seqcount, so that we get a consistent snapshot. Note that mpls_label_ok is also susceptible to this, so the check against RTA_DST in rtm_to_route_config, done outside platform_mutex, is not sufficient. This value gets passed to mpls_label_ok once more in both mpls_route_add and mpls_route_del, so there is no issue, but that additional check must not be removed.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2026-43042 since 05/01/2026. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 05/01/2026).

Upgrading to version 6.19.12 eliminates this vulnerability. Applying the patch 5bb3caf0bbfb56f1a00d2af072ac3d8395a3b9ef/629ec78ef8608d955ce217880cdc3e1873af3a15 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.19.0
• 6.19.1
• 6.19.2
• 6.19.3
• 6.19.4
• 6.19.5
• 6.19.6
• 6.19.7
• 6.19.8
• 6.19.9
• 6.19.10
• 6.19.11

License

• open-source

Website

• Vendor: https://www.kernel.org/

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