If you look up this word, 言う, in a dictionary of old Japanese, the first two meanings are:
One point I think that is worth pointing out here is that Japanese does not use explicit passive constructions as you do in English. Consider this illustrative sentence.
This house was built by my father.
The use of active and passive construction are different between Japanese and English, and there are some cases of Japanese favouring an active construction, while English uses a passive one. Passive constructions are used in English for various reasons including (1) avoiding mentioning the agent, (2) shifting focus (by moving
house to the front and making it the subject).
Note that Japanese does not require a subject for a complete sentence, thus eliminating reason (1) for using a passive construction.
With that in mind, we can understand why a phrase such as
Ｘという問題 can be interpreted as
a question/problem that is called X, even though there is no explicit passive construction in the original phrase.
This is described in this book as well:
The function of the predicative form [終止形, =連体形 in mod. Japanese] is to predicate, without reference to time. It is true that, being neutral as to time, it can usually be translated by a present tense in English; but context may demand other tenses. [...] In common with other forms of the verb, the Predicative is neutral as to person. [...] This characteristic is exhibited in a most interesting way in such common constructions as
kono mura wa Kose to iū this village is called Kose
The idea of person or agent is neither expressed nor implicit in the verb iū. In English, the corresponding locution requires the passive voice, which is a grammatical device used when we wish to describe an act without reference to the agent. In Japanese, an active verb is used, because the use of an active verb does not involve mention of the subject.
(An historical grammar of Japanese, George Sansom, Oxford at the Clarendon Press, 4th ed. 1968, page 131-132)