How strict is Cambodia about the 6 months passport expiration requirement? Just realized daughter's passport expires just under 6 months. (5 months left). Somehow was allowed into Vietnam with the same passport. Flying Vietnam Air.

I always take such requirements seriously, even though they may not be enforced regularly. They can be enforced on a whim by any immigration officer anywhere. Sometimes an airline will enforce it when checking in.

If you can’t get her passport renewed in time, even expedited, then have a Plan B, just in case. It would be foolish to ignore the possibility.

Agree with the above comments , there is a reason that governments have these regulation and your daughter ignores them at here peril.

The two ways to get in (depending upon your nationality, are via the Evisa scheme and the visa on arrival at the airport. I doubt she would get the Evisa as her passport doesn't qualify. At the departure airport it is highly likely that Vietnam Air would not let her board the flight as it is they who are responsible for send her back to her destination. At PP or SR airport the immigration officers may take pity on her as they sometimes allow visitors through if they have 3 months left and have an onwardticket.

Bear in mind that Cambodia officials are considered by some to be corrupt and it is common to be asked for "admin fees" to cover such infractions! (it is the norm at land borders to be asked for bribes even if everything is in order.

It is no fun being challenged at a border as I once found out . I once tried to enter Vietnam days after they change the visa rules but no one had told the immigration people at Kuala Lumpur airport! I was refused boarding, missed the flight and spent the best part of a day collating all teh info online to prove to the border people that I was right and they were wrong. I eventually got where I was going but it was an expensive and time consuming hassle.

If at all possible I would renew the passport using an expedited service.

Is she currently in Vietnam? She should probably try to get an emergency appointment at the embassy. If Cambodia is the last country on her trip, perhaps she can stay in Vietnam longer, then fly home from there?