Their withdrawals gave Belinda Bencic (25) and Daria Kasatkina (25) free rides into Saturday's title match.
Russia's Kudermetova, seeded nine for the opening Grand Slam of the year, which starts Monday, cited a left hip injury for her pull-out against Switzerland's Bencic.
It followed epic three-setters in her two previous matches, with her quarter-final against Danielle Collins on Thursday extending beyond three hours.
Olympic champion Bencic, who has won nine of her last 10 matches, is aiming to claim a sixth singles trophy and her fifth on a hard court.
She will face world number eight Kasatkina, who is gunning for a seventh WTA title and her second in Australia, having claimed the Phillip Island Trophy last year.
Kasatkina progressed when Spain's Paula Badosa, seeded 11th at Melbourne Park, opted out because of a thigh injury.
"Yesterday when I was playing it was a very tough match, especially physical, so I felt a little bit in my abductor. I felt like I pulled it a little bit," said Badosa.
The Spaniard battled through a gruelling quarter-final clash with Brazil's Beatriz Haddad Maia that stretched beyond two-and-a-half hours.
"Today I feel a little bit worse, I have the Australian Open ahead, and I hope I can recover for that," she added.
The Grand Slam has been hit by numerous withdrawals in both the men's and women's fields, including two-time former champion Naomi Osaka, who is expecting her first child.
