CVE-2026-98485 Linux CVE debrief

Who should care

Defenders responsible for Linux kernel systems with netfilter enabled should assess exposure and prioritize patching. They should also monitor for unusual IPv6 packet processing behavior.

Why it matters

The Linux kernel vulnerability in the netfilter component allows for out-of-bounds reads when processing IPv6 packets. Defenders should prioritize patching and monitoring to prevent potential kernel panics or warnings.

• Verify and apply patches to prevent out-of-bounds reads
• Monitor for unusual IPv6 packet processing behavior
• Review and update netfilter rules to prevent zero-address configurations with address matching
• Assess exposure and prioritize patching for Linux kernel systems with netfilter enabled

Technical summary

The vulnerability is caused by the ip6t_rt module's handling of IPv6 packets with routing addresses. When a rule is configured with address matching requested but zero addresses provided, a crafted IPv6 packet can cause the packet processing to read beyond the struct ip6t_rt. This leads to UBSAN/KASAN out-of-bounds warnings or kernel panics. The fix involves rejecting such rules and modifying the packet processing loop.

Defensive priority

Defenders should prioritize verifying and applying patches for this vulnerability, particularly for systems using the Linux kernel with netfilter enabled. They should also monitor for unusual IPv6 packet processing behavior.

Recommended defensive actions

• Verify and apply patches for this vulnerability
• Monitor for unusual IPv6 packet processing behavior
• Review and update netfilter rules to prevent zero-address configurations with address matching
• Perform an asset inventory to identify potentially affected systems
• Implement compensating controls for exposed systems while remediation is scheduled
• Review and adjust rollback/change windows for patch deployment
• Track and verify remediation of affected assets

Evidence notes

The vulnerability was resolved in the Linux kernel through a series of commits that reject rules with zero addresses when address matching is requested and modify the packet processing loop to prevent out-of-bounds reads.

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.