snap-confine as included in snapd before 2.39 did not guard against symlink races when performing the chdir() to the current working directory of the calling user, aka a "cwd restore permission bypass."

snap-confine in snapd before 2.38 incorrectly set the ownership of a snap application to the uid and gid of the first calling user. Consequently, that user had unintended access to a private /tmp directory.