CVE-2023-53821

A use-after-free vulnerability was found in the IPv6 VTI (Virtual Tunnel Interface) implementation in the Linux kernel. When an IPv6 VTI device uses the SFB (Stochastic Fair Blue) qdisc, the control block (cb) field of an skb can be modified during packet enqueuing. The decode_session6() function then reads from this modified cb field, accessing freed memory (IP6CB(skb)->nhoff was not set for transmit path). This can lead to kernel crashes or potentially arbitrary code execution.

This is a use-after-free vulnerability in IPv6 VTI tunnel handling that can be triggered when specific qdisc configurations are used. The vulnerability requires local access and specific network configuration involving VTI tunnels with SFB qdisc.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.