CVE-2025-21826: linux kernel — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: reject mismatching sum of field_len with set key length The field length description provides the length of each separated key field in the concatenation, each field gets rounded up to 32-bits to calculate the pipapo rule width from pipapo_init(). The set key length provides the total size of the key aligned to 32-bits. Register-based arithmetics still allows for combining mismatching set key length and field length description, eg. set key length 10 and field description [ 5, 4 ] leading to pipapo width of 12.

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CVSS v3.1 Score

5.5

MEDIUM

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

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.10.209 — 5.10.235
linux	linux_kernel	5.15.148 — 5.15.179
linux	linux_kernel	6.1.75 — 6.1.129
linux	linux_kernel	6.6.14 — 6.6.76
linux	linux_kernel	6.7.2 — 6.12.13
linux	linux_kernel	6.13 — 6.13.2

References

Advisories & Patches

https://git.kernel.org/stable/c/1b9335a8000fb70742f7db10af314104b6ace220 https://git.kernel.org/stable/c/2ac254343d3cf228ae0738b2615fedf85d000752 https://git.kernel.org/stable/c/49b7182b97bafbd5645414aff054b4a65d05823d https://git.kernel.org/stable/c/5083a7ae45003456c253e981b30a43f71230b4a3 https://git.kernel.org/stable/c/6b467c8feac759f4c5c86d708beca2aa2b29584f https://git.kernel.org/stable/c/82e491e085719068179ff6a5466b7387cc4bbf32 https://git.kernel.org/stable/c/ab50d0eff4a939d20c37721fd9766347efcdb6f6

Other References

https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html https://cert-portal.siemens.com/productcert/html/ssa-265688.html https://cert-portal.siemens.com/productcert/html/ssa-503939.html

Frequently Asked Questions

What is CVE-2025-21826? +

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: reject mismatching sum of field_len with set key length The field length description provides the length of each separated key field in the concatenation, each field gets rounded up to 32-bits to calculate the pipapo rule width from pipapo_init(). The set key length provides the total size of the key aligned to 32-bits. Register-based arithmetics still allows for combining mismatching set key length and field length description, eg. set key length 10 and field description [ 5, 4 ] leading to pipapo width of 12. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-21826? +

CVE-2025-21826 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-21826? +

CVE-2025-21826 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-2025-21826? +

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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