CVE-2026-89565 Linux CVE debrief

Who should care

Linux kernel developers and administrators responsible for maintaining and securing Linux-based systems, particularly those using ipip or mplsip tunnels in collect_md mode, should assess exposure and verify patches.

Why it matters

CVE-2026-89565 is a Linux kernel vulnerability that can cause a skb leak in collect_md mode. Linux kernel developers and administrators should assess exposure, verify patches, and monitor for potential issues.

• Potential packet leakage in collect_md mode
• Need to verify and apply patches for Linux kernel ipip tunnel driver
• Possible impact on network packet processing and forwarding
• Requires monitoring for potential skb leaks

Technical summary

The Linux kernel's ipip tunnel driver has a vulnerability that can cause a skb leak in collect_md mode when metadata_dst allocation fails. ipip_tunnel_rcv() returns 0 without freeing the skb, and tunnel4_rcv() and tunnelmpls4_rcv() do not free it either. The fix involves jumping to the existing drop label to free the skb and return 0. This vulnerability can lead to potential packet leakage in collect_md mode, requiring verification and application of patches for Linux kernel ipip tunnel driver. It is essential to review compensating controls for exposed systems while remediation is scheduled and verified.

Defensive priority

Verify and apply patches for Linux kernel ipip tunnel driver

Recommended defensive actions

• Verify Linux kernel version and ipip tunnel driver configuration
• Apply patches for Linux kernel ipip tunnel driver
• Monitor for potential skb leaks in collect_md mode
• 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
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide details on the vulnerability. However, the corpus does not establish versions, exploitation, impact, or remediation, which require verification from official sources.

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.