Any guest issuing a Xenstore command accessing a node using the (illegal) node path "/local/domain/", will crash xenstored due to a clobbered error indicator in xenstored when verifying the node path.
Note that the crash is forced via a failing assert() statement in xenstored. In case xenstored is being built with NDEBUG #defined, an unprivileged guest trying to access the node path "/local/domain/" will result in it no longer being serviced by xenstored, other guests (including dom0) will still be serviced, but xenstored will use up all cpu time it can get.
Exploitability
AV:LAC:LPR:NUI:NScope
S:CImpact
C:NI:NA:H7.1/CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H