Context (New York Times),
The episode has been a sobering lesson in how even an agency that carries some 350,000 passengers over 104 miles of track every workday can be brought low by a seemingly ragtag group of activists who identify themselves by pseudonyms like Lamaline_5mg.
In Oxford Advanced Learner's Dictionary, I found this entry,
be brought low (old-fashioned) to lose your wealth or your high position in society
But I'm wondering if we can just simply interpret this idiom literally? Please see these two entries in Merriam-Webster,
bring: (4) : to cause to come into a particular state or condition.
low: 11: unfavorable, disparaging