European soccer's governing body said Eremenko had failed a doping test following CSKA's 2-2 Champions League draw against Bayer Leverkusen on Sept. 14.
"The analysis of the A sample revealed the presence of cocaine and its metabolites," UEFA said in a statement on their website (www.uefa.com).
Eremenko was originally banned for 30 days in October, although no reason was given for the suspension at that time.
The midfielder, 29, had scored a 38th-minute equaliser against Leverkusen as CSKA fought back from two goals down to snatch a draw.
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"The club is going to appeal the decision together with the player," CSKA said in a statement.
Eremenko is a key player for Finland, who have lost all of their three World Cup qualifiers since he was suspended.
The Finnish Football Association issued a statement expressing disappointment with the player.
"A use of narcotics can not be accepted in any circumstances," General Secretary Marco Casagrande said.
(Reporting by Jussi Rosendahl, additional reporting by Vladimir Soldatkin in Moscow; Editing by Toby Davis)
