Yutaka Niibe at
... in the development version recently.
I wrote this based on this comment:
https://bugzilla.redhat.com/show_bug.cgi?id=1413618#c3
But it seems that Curve25519 is already available in F26, with libgcrypt-1.7. If so, security fix by libgcrypt-1.7.9 should be used.