CVE-2026-98101 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Linux distribution maintainers, system administrators responsible for Linux systems using IPv6 multicast, and security teams should verify their systems' kernel versions and configurations, apply the patch if necessary, and monitor for potential issues. The vulnerability affects Linux systems that utilize IPv6 multicast handling, and its resolution is crucial for maintaining the security and integrity of these

Why it matters

A vulnerability in the Linux kernel's IPv6 multicast handling has been addressed. The ip6_mc_source() function was updated to use copy-on-write RCU updates to prevent torn reads by concurrent readers. Linux kernel developers, maintainers, and system administrators should verify their systems' kernel versions and configurations, apply the patch if necessary, and monitor for potential issues.

• Verification of Linux kernel version and configuration is required to determine if systems are affected.
• Applying the kernel patch is necessary to prevent potential issues with IPv6 multicast handling.
• Monitoring for potential issues with IPv6 multicast handling is recommended.

Technical summary

The Linux kernel's IPv6 multicast handling had a vulnerability where in-place updates to source filters could lead to torn reads by concurrent readers. This was addressed by switching ip6_mc_source() to use copy-on-write RCU updates, ensuring that new source filters are fully populated before being published. The update prevents potential issues with IPv6 multicast handling by ensuring that concurrent readers do not encounter torn reads or duplicated/missed source entries. The fix is applicable to Linux kernel developers, maintainers, and system administrators responsible for Linux systems using IPv6 multicast.

Defensive priority

Medium

Recommended defensive actions

• Review and apply the kernel patch to ensure copy-on-write RCU updates are used in ip6_mc_source().
• Verify the Linux kernel version and configuration to determine if the system is affected.
• Monitor for potential issues with IPv6 multicast handling.
• 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.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review compensating controls for exposed systems while remediation is scheduled and verified.

Evidence notes

The CVE record and NVD entry provide details on the vulnerability. However, the scope of affected systems and versions is not explicitly stated, requiring verification from official sources. The Linux kernel's IPv6 multicast handling had a vulnerability where in-place updates to source filters could lead to torn reads by concurrent readers. This was addressed by switching ip6_mc_source() to use copy-on-write RCU updates, ensuring that new source filters are fully populated before being published. The fix prevents potential issues with

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.