CVE-2026-63999 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Linux distribution maintainers, users of Linux systems with ethtool functionality, and security teams responsible for vulnerability management.

Technical summary

In the Linux kernel, a vulnerability was found in the ethtool RSS (Receive Side Scaling) functionality. The rss_prepare_get() function allocates memory for the indirection table and hash key buffer using rss_get_data_alloc(). If the subsequent ops->get_rxfh() call fails, the allocated memory is not freed, resulting in a memory leak. This issue has been resolved by ensuring proper memory cleanup in case of get_rxfh() failure.

Defensive priority

Medium priority for Linux kernel developers and maintainers

Recommended defensive actions

• Review and apply the provided kernel patches to fix the memory leak issue
• Update Linux kernel to the latest version
• Monitor Linux kernel updates and patches for similar issues
• 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
• 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

Evidence notes

The CVE record was published on 2026-07-19T16:17:39.477Z and has not been modified since then. The NVD entry is currently Received. The vulnerability was resolved in the Linux kernel. There is no evidence of exploitation in the wild. The vulnerability affects Linux kernel deployments. Defenders should verify Linux kernel versions and apply patches if necessary.

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.