Cox was signed off the Giants' practice squad. Starting running back Rashad Jennings injured his left knee on Sunday in the win over Atlanta.
Hosley was reinstated after serving a four-game suspension for violating the NFL's policy on substances of abuse. He had a roster exemption last week.
Talley was signed off the practice squad on Sept. 16. He played against Houston and Washington, but was inactive Sunday. Fenner was signed off the practice squad on Saturday and played on special teams on Sunday.
Cox played in 14 games with the Giants last season and returned 20 kickoffs, averaging 21.8 yards. He was waived on Aug. 30.
A third-round draft pick in 2012, Hosley has played in 23 games with seven starts.
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