  We directly measure twenty overhanging cliffs on the surface of comet
67P/Churyumov-Gerasimenko extracted from the latest shape model and estimate
the minimum tensile strengths needed to support them against collapse under the
comet's gravity. We find extremely low strengths of around one Pa or less (one
to five Pa, when scaled to a metre length). The presence of eroded material at
the base of most overhangs, as well as the observed collapse of two features
and implied previous collapse of another, suggests that they are prone to
failure and that true material strengths are close to these lower limits
(although we only consider static stresses and not dynamic stress from, for
example, cometary activity). Thus, a tensile strength of a few pascals is a
good approximation for the tensile strength of 67P's nucleus material, which is
in agreement with previous work. We find no particular trends in overhang
properties with size, over the $\sim10-100$ m range studied here, or location
on the nucleus. There are no obvious differences, in terms of strength, height
or evidence of collapse, between the populations of overhangs on the two
cometary lobes, suggesting that 67P is relatively homogenous in terms of
tensile strength. Low material strengths are supportive of cometary formation
as a primordial rubble pile or by collisional fragmentation of a small (tens of
km) body.
