CVE-2026-64113 Linux CVE debrief

Who should care

Linux kernel users and administrators should be aware of this vulnerability and take steps to defend against it. This includes updating to the latest kernel version or applying specific patches. System administrators responsible for Linux-based systems, especially those using the ixgbevf driver, should review their systems for exposure and apply necessary mitigations.

Technical summary

The vulnerability occurs in the ixgbevf_clean_rx_irq() function, where the skb pointer is declared outside the while loop and persists across iterations. When the skb is freed and the loop continues, the next iteration enters the 'else if (skb)' path and calls ixgbevf_add_rx_frag() on the freed skb, leading to a use-after-free in NAPI softirq context. The issue can be resolved by nulling the skb pointer before continuing, similar to the sibling driver iavf. This vulnerability can be addressed by updating the Linux kernel to the latest version, which includes the fix.

Defensive priority

High

Recommended defensive actions

• Update the Linux kernel to the latest version
• Disable the ixgbevf driver if not needed
• Monitor for suspicious activity
• 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 vulnerability was found by static analysis and confirmed under KASAN by loading a test module that reproduces the exact code pattern. The analysis was performed using scan_drop_continue_loops.py and semgrep drop_continue_in_loop, with multi-tool corroboration. The UAF was confirmed under KASAN by loading a test module that reproduces the exact code pattern (alloc skb, kfree_skb, then read skb_shinfo(skb)->nr_frags). The bug was confirmed in a controlled environment with QEMU emulation. Linux kernel users should verify their systems for exposure and apply patches or mitigations as needed.

Official resources