In Norlin v. Montgomery the Washington court (1) held that a mortgagee of the vendee's interest under a forfeitable real estate contract has a lien on the equity of the vendee, and (2) implied that the lien survives a default by the vendee and a subsequent declaration of forfeiture by the vendor.
Washington Case Law,
Security Transactions—Survival of Mortgage-Lien on Conditional Vendee's Interest Following Declaration of Forfeiture,
Wash. L. & Rev.
Available at: https://digitalcommons.law.uw.edu/wlr/vol37/iss2/16