  Evidences have been found that the weak cosmic censorship conjecture could be
violated if test particles with charge and angular momentum are injected into a
black hole. However, second-order corrections and fine-tunings on the
particle's parameters are required in previous studies, indicating that
self-force and radiative effects must be taken into account. In this paper, we
first consider a magnetically charged particle falling into an extremal Bardeen
black hole, which is regular (with no singularity) and has a magnetic monopole
at the center. We then investigate a general class of magnetic black holes with
or without singularities. In all the cases, we show that the test particle with
magnetic charge could overcharge the black hole, causing possible violation of
the weak cosmic censorship conjecture. In contrast to previous arguments in the
literature, second-order corrections are not necessary in our analysis and the
results are not sensitive to the particle's parameters. Our work indicates that
the self-force effect, which is related to the second-order correction, may not
help rescue the weak cosmic censorship conjecture in our examples.
