Jon Heyman of FanRag Sports reported Sandoval would "love" to go back to the Giants and that "some Giants people have spoken behind the scenes about the possibility, and they suggest it could be a consideration."
Since Sandoval was designated for assignment, the Red Sox have 10 days to try to find a trade partner before he can be released.
The 30-year-old signed a five-year, $95 million deal with the Red Sox in November 2014. His contract quickly became an albatross for the team, as he hit just .237/.286/.360 with 14 home runs in 161 games.
Prior to joining the Red Sox, Sandoval was one of the cornerstones of the Giants' run of three World Series titles in five years from 2010 to 2014. He hit .294/.346/.465 in seven seasons in San Francisco, was named to the National League All-Star team in 2011 and 2012 and won World Series MVP honors in 2012.