The primary sources, both chronicles, are cited in the article, reproduced in the Monumenta Germaniae Historica (a series of edited Medieval texts, known for be

The primary sources, both chronicles, are cited in the article, reproduced in the Monumenta Germaniae Historica (a series of edited Medieval texts, known for being carefully edited). There could be issues, of course, like the original authors of the chronicles making up the stories, but this isn't just a baseless Wikipedia hoax. The Chronicle of Reinhardsbrunn, at least, does make specific mention that the nobles fell into a cesspit (cloaca) and died miserably by suffocating in the filth (sceno suffocati miserabiliter interierunt).