CVE-2026-98929 Linux CVE debrief

Who should care

Defenders responsible for Linux systems using MACsec and LRO should assess exposure and prioritize patching. This vulnerability can cause warnings and report uninitialized SecY attributes in notifications during MACsec device creation.

Why it matters

This vulnerability in the Linux kernel's MACsec implementation can cause warnings and report uninitialized SecY attributes in notifications. Defenders should prioritize patching and review system configurations to assess exposure.

• Defenders must verify and apply patches to prevent warnings and ensure proper SecY initialization.
• System administrators should review configurations for MACsec and LRO usage to assess exposure.
• Security teams should monitor for notifications related to MACsec device creation to detect potential issues.

Technical summary

The Linux kernel's MACsec implementation did not initialize the SecY before registering the netdevice. This caused warnings when creating a MACsec device with MAC offload over an LRO-capable lower device. The issue has been resolved by initializing the SecY and applying new-link attributes before registration. Defenders should prioritize verifying and applying patches for this vulnerability, especially for systems using MACsec and LRO. The vulnerability is caused by the ordering of operations during MACsec device creation. The SecY must be initialized before registering the netdevice to prevent warnings and ensure that notifications report initialized attributes.

Defensive priority

Defenders should prioritize verifying and applying patches for this vulnerability, especially for systems using MACsec and LRO.

Recommended defensive actions

• Verify and apply patches for this vulnerability
• Review system configurations for MACsec and LRO usage
• Monitor for warnings and notifications related to MACsec device creation
• Perform vulnerability assessment to identify potential exposure
• Implement compensating controls for exposed systems
• Track exceptions and retest remediated assets
• Review asset inventory for affected products

Evidence notes

The vulnerability is caused by the ordering of operations during MACsec device creation. The SecY must be initialized before registering the netdevice to prevent warnings and ensure that notifications report initialized attributes.

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.