CVE-2026-89459 Linux CVE debrief

Who should care

Linux kernel maintainers, administrators, and users of systems with older binutils versions should assess exposure and verify system configurations. This includes reviewing Linux kernel configurations for potential exposure and verifying system vulnerability to incorrect per-CPU address handling. Additionally, users should ensure that their systems are updated with the official patches to prevent potential issues.

Why it matters

A Linux kernel vulnerability was addressed, involving the MVIY_PERCPU() macro and its interaction with older binutils versions.

• Verify Linux kernel configurations for potential exposure.
• Assess system vulnerability to incorrect per-CPU address handling.

Technical summary

The Linux kernel vulnerability involves a fix for the MVIY_PERCPU() macro, which had issues with older binutils versions, potentially leading to incorrect per-CPU address handling. The fix ensures compatibility with GNU as versions prior to binutils 2.39 and prevents assembler macro invocation issues. This change was introduced to address the vulnerability and ensure proper handling of per-CPU address registers in the Linux kernel. The technical details involve using C string literals directly and separating assembler macro arguments with an explicit comma.

Defensive priority

Assess exposure in Linux kernel deployments, particularly those using older binutils versions, and verify system configurations against official patches.

Recommended defensive actions

• Assess Linux kernel deployments for exposure, particularly with older binutils versions.
• Verify system configurations against official patches.
• Inventory and update affected systems.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• Review compensating controls for exposed systems while remediation is scheduled and verified.

Evidence notes

The issue arises from the MVIY_PERCPU() macro's interaction with GNU as versions prior to binutils 2.39, which could result in assembler macro invocation issues. The fix involves using C string literals directly and separating assembler macro arguments with an explicit comma. This change prevents assembler macro invocation issues and ensures proper handling of per-CPU address registers. The vulnerability was addressed in the Linux kernel, and users should verify their system configurations against official patches.

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.