Old Church Slavonic is another language with strictly open syllables.
Exceptions might be some foreign words. The dictionary (Cejtlin, Večerka, Bláhová, 1994) has both елинъ and еллинъ (and also елиньнъ) - Greek.
Latvian and Hebrew do not allow double consonants. Even when mentioning names of people from other languages they will drop the second consonant. Thus Wasserman becomes Waserman in both languages. Any other languages with this property?