CVE-2025-21818

[REJECTED CVE] In the Linux kernel, the following vulnerability has been resolved:

x86/xen: fix xen_hypercall_hvm() to not clobber %rbx

xen_hypercall_hvm(), which is used when running as a Xen PVH guest at most only once during early boot, is clobbering %rbx. Depending on whether the caller relies on %rbx to be preserved across the call or not, this clobbering might result in an early crash of the system.

This CVE has been marked as Rejected by the assigning CNA.