  If light supersymmetric top (stop) quarks are produced at the LHC and decay
via on- or off-shell $W$-bosons they can be expected to contribute to a
precision $W^+W^-$ cross section measurement. Using the latest results of the
CMS experiment, we revisit constraints on the stop quark production and find
that this measurement can exclude portions of the parameter space not probed by
dedicated searches. In particular we can exclude light top squarks up to
230~GeV along the line separating three- and four-body decays, $\tilde{t}_1 \to
\tilde{\chi}_1^0 W^{(*)} b$. We also study the exclusion limits in the case
when the branching ratio for these decays is reduced and we show significant
improvement over previously existing limits.
