The Linux kernel contains a NULL pointer dereference in the address family iucv callback for handling SYN packets. When child socket allocation fails, the code unconditionally calls iucv_sock_kill() with a NULL parameter. iucv_sock_kill() immediately dereferences the socket pointer, causing a kernel crash. The confirmed impact is a denial‑of‑service that can bring the entire system down when the vulnerability is exercised.

All Linux distributions that ship a kernel version including the traditional iucv networking code and preceding the commit that introduced the fix are affected. No specific kernel version numbers are listed, so any kernel containing the pre‑patch code for afiucv_hs_callback_syn() is at risk.

No CVSS score is provided, and the EPSS score is not available; the vulnerability is not listed in the CISA KEV catalog. The lack of data does not diminish the potential severity of a kernel crash. The likely attack vector is local or requires elevated privileges to trigger the fault via iucv connection attempts. Because the flaw leads to an immediate crash, the risk is high once the code path is exercised. However, without evidence of active exploitation, the overall threat remains limited to unpatched systems.