CVE-2026-45897 Linux CVE debrief

Who should care

Linux kernel maintainers, users, and administrators should assess exposure and apply patches for CVE-2026-45897. Linux kernel versions 6.1.107 to 6.2 and 6.6.48 to 6.19.4 are affected. The vulnerability has been resolved by adding a global static spinlock to serialize counter fetch+reset operations. This change prevents potential underruns of counter values during concurrent access, enhancing the stability and security of the Linux kernel's netfilter.

Why it matters

CVE-2026-45897 is a medium-severity vulnerability in the Linux kernel's netfilter component. Linux kernel maintainers and users should assess exposure and apply patches to prevent potential underrun of counter values.

• Verify Linux kernel versions and apply patches to prevent potential underrun of counter values
• Monitor Linux kernel updates for potential future vulnerabilities
• Review and update Linux kernel configurations to ensure secure settings

Technical summary

The Linux kernel's netfilter component has a vulnerability in the nft_counter. A global static spinlock has been added to serialize counter fetch+reset operations, preventing concurrent dump-and-reset from underrunning values. This fix enhances the stability and security of the Linux kernel's netfilter component by ensuring accurate counter updates during concurrent access. Linux kernel maintainers and users should assess exposure and apply patches to prevent potential underrun of counter values. The vulnerability has been resolved by adding a global static spinlock to serialize counter fetch+reset operations.

Defensive priority

Medium priority for Linux kernel maintainers and users to apply patches for CVE-2026-45897

Recommended defensive actions

• Apply patches from Linux kernel maintainers
• Review and update Linux kernel versions to ensure patched versions are used
• Monitor Linux kernel updates for potential future vulnerabilities
• Verify Linux kernel configurations to ensure secure settings
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and NVD entry provide details on the vulnerability. Linux kernel versions 6.1.107 to 6.2 and 6.6.48 to 6.19.4 are affected. The vulnerability has been resolved by adding a global static spinlock to serialize counter fetch+reset operations. This fix ensures that counter values are accurately updated and prevents underruns during concurrent dump-and-reset operations.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.