The Exiles prop was selected to start Saturday's Aviva Premiership clash at Gloucester, but he was a late withdrawal because of persistent knee trouble.
England kick off their RBS 6 Nations campaign in four weeks' time, and there must be considerable doubt about Corbisiero's prospects, although he started recent autumn Tests against South Africa and New Zealand.
"It is very frustrating for us, it is very frustrating for 'Corbs'. It is a tough time for him, and it is a difficult one to balance," Smith said, following his team's 18-12 Kingsholm success.
"His knee is a mess. He has played one-and-a-half games for us this season, and it is very disappointing.
"Sitting here right now, I couldn't tell you if he is going to play next week or not. He has got degenerative knee issues.
"He trained twice this week. We are bringing him back, and then at the captain's run he pulled out prior to it, and we had to make a change.
"There is not much of a decision to make when a bloke's knee has blown up and he feels he can't play. You can't put a gun to his head and tell him to get on the paddock.
"He is an honest person, he is a good bloke. He desperately wants to play for us, but it is a very frustrating situation."
Even without Corbisiero, relegation candidates Irish ripped up the Premiership form book by stunning title play-off contenders Gloucester.
Irish had already lost three times to their hosts in domestic and European competitions this season, but two first-half tries from lock George Skivington helped the Exiles exact revenge.
Centre Steven Shingler added a penalty and conversion, while England international Freddie Burns booted four Gloucester penalties, yet Irish deserved a first Premiership away victory this season at the seventh attempt, which was sealed by full-back Tom Homer's late penalty.
It took them five points above bottom club Sale Sharks, who tackle Saracens tomorrow, and sent them into a five-week league break with renewed optimism of avoiding the drop.
Smith added: "We picked a big pack so we could go toe-to-toe with them. The game could have gone either way, that is fair to say, but we came out on top.
"The team showed a lot of character and toughed it out. I thought the whole pack was immense today. It was won up front."
In contrast, Gloucester rugby director Nigel Davies had few complaints after his team suffered a first home defeat since September 1.
"We are hugely disappointed," Davies said. "For whatever reason, as a group, we got it wrong today. We don't think that is acceptable.
"The important thing is that when you lose games, it's how you deal with it, manage it and come back. Today showed we are not good enough to slip off the hard work, intensity and accuracy.
"When we do that, like we we did today, then we were second best.
"We had little control over the game. Our set-piece didn't function, which put a bit of pressure on us, and there were far too many errors in our game."
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