  We present extensive new \emph{ab initio} path integral Monte Carlo (PIMC)
results for the spin-resolved density response of the uniform electron gas
(UEG) at warm dense matter conditions. This allows us to unambiguously assess
the accuracy of previous theoretical approximations, thereby providing valuable
new insights for the future development of dielectric schemes. From a physical
perspective, we observe a nontrivial manifestation of an effective
electron--electron attraction that emerges in the spin-offdiagonal static
density response function at strong coupling, $r_s\gtrsim5$. All PIMC results
are freely available online and can be used to benchmark new approximations and
simulation schemes.
