  The distribution of gas in the circumgalactic medium (CGM) of galaxies of all
types is poorly constrained. Foreground CGMs contribute an extra amount to the
dispersion measure (DM) of fast radio bursts (FRB). We measure this DM excess
for the CGMs of $10^{11}-10^{13}\ M_\odot$ halos using the CHIME/FRB first data
release, a halo mass range that is challenging to probe in any other way.
Because of the uncertainty in the FRBs' angular coordinates, only for nearby
galaxies is the localization sufficient to confidently associate them with
intersecting any foreground halo. Thus we stack on galaxies within 80 Mpc,
optimizing the stacking scheme to approximately minimize the stack's variance
and marginalize over uncertainties in FRB locations. The sample has 20-30 FRBs
intersecting halos with masses of $10^{11}-10^{12}\ M_\odot$ and also of
$10^{12}-10^{13}\ M_\odot$, and these intersections allow a marginal
$1-2\,\sigma$ detection of the DM excess in both mass bins. The
$10^{11}-10^{12}\ M_\odot$ halos bin also shows a DM excess at 1-2 virial
radii. By comparing data with different models for the CGM gas profile, we find
that all models are favored by the data up to 2-$\sigma$ level compared to the
null hypothesis of no DM excess. With 2000-3000 more bursts from a future CHIME
data release, we project a 4-$\sigma$ detection of the CGM. Distinguishing
between viable CGM models by stacking FRBs with CHIME-like localization would
require tens of thousands of bursts.
