CVE-2024-56558 is a use-after-free vulnerability in the Linux kernel's NFS daemon (nfsd). The issue arises because the function e_show was called with only RCU protection, which prevents freeing but does not prevent the reference count from dropping to zero. This can lead to a refcount use-after-free warning when exp_get is called. The flaw was fixed by using cache_get_rcu to ensure the exp object remains active during access.