From the viewport height (vh) specification , it does not mention that there is a minimum / maximum limit. However, in Section 5 of CSS Values and Units: Numerical Data Types , he mentions that:
CSS theoretically supports infinite precision and infinite ranges for all types of values; however, in reality, implementations have limited capacity. UAs must support reasonably useful ranges and prefixes.
and some SO users check the value limit for each browser , and the results are as follows:
Firefox: 33554400px Chrome: 33554428px Opera: 33554428px IE 9: 21474836.47px
and the behavior described above is explained in Section 5: Distance Units :
Although some properties allow negative lengths, this can complicate formatting, and there may be implementation restrictions. If a negative length value is allowed but not supported, it should be converted to the closest value that can be supported.
Hope the above can answer your question.