How big of a concern is galvanized water supply line?

[Albert L.]

Hello, home inspection came back for a 1977 home that state:

"Observed a galvanized water supply line in attic over master bedroom was heavily

corroded appears to be leaking. This is common with older galvanized pipe systems and

there may be more of this in areas that were not accessible. We recommend further

inspection by a licensed plumber and repair as necessary."

How concerned should I be? Thanks!