Amazon Linux 2023: CVE-2025-21764: Important priority package update for kernel

In the Linux kernel, the following vulnerability has been resolved:
ndisc: use RCU protection in ndisc_alloc_skb()
ndisc_alloc_skb() can be called without RTNL or RCU being held.
Add RCU protection to avoid possible UAF.
A vulnerability was found in the Linux kernel's IPv6 Neighbor Discovery (NDISC) subsystem, which manages network neighbor information. The issue arises from improper synchronization mechanisms when allocating socket buffers (sk_buff) in the ndisc_alloc_skb() function. Specifically, the function can be called without holding the necessary Read-Copy-Update (RCU) or Routing Netlink (RTNL) locks, leading to a potential use-after-free (UAF) condition. This flaw allows an attacker with local access and low privileges to exploit the race condition, potentially causing system instability or crashes.