  Within the Borel QCD sum rule approach at finite baryon density we study the
role of the four-quark condensates for the modifications of the vector mesons
$\rho$, $\omega$ and $\phi$ in nuclear matter. We find that in-medium
modifications of the $\rho$ and $\omega$ mesons are essentially dominated by
the dependence of the 4-quark condensate on the nucleon density. In particular,
the numerical value of a parameter ($\kappa_N$), which describes the strength
of the density dependence of the 4-quark condensate beyond the mean-field
approximation, governs the decrease of the $\rho$ mass as a function of the
density. For the $\omega$ meson the sign of the in-medium mass shift is changed
by variations of $\kappa_N$. To study consistently the in-medium broadening of
the light vector mesons we employ $\rho N$ and $\omega N$ scattering amplitudes
derived recently from a covariant unitary coupled channel approach adjusted to
pion- and photo-induced reactions. In contrast to the $\rho$ and $\omega$
mesons, the in-medium mass of the $\phi$ meson is directly related to the
chiral (strange) quark condensate. Measurements of the vector meson spectral
change in heavy-ion collisions with HADES can shed light on the yet unknown
density dependence of the 4-quark condensate.
