  We propose a tune-free scheme to realize Kramers pairs of Majorana bound
states in recently discovered higher-order topological insulators (HOTIs). We
show that, by bringing two hinges of a HOTI into the proximity of an $s$-wave
superconductor, the competition between local and crossed-Andreev pairing leads
to the formation of Majorana Kramers pairs, when the latter pairing dominates
over the former. We demonstrate that such a topological superconductivity is
stabilized by moderate electron-electron interactions. The proposed setup
avoids the application of a magnetic field or local voltage gates, and requires
weaker interactions compared with nonhelical nanowires.
