"PuTTY 0.59 and earlier uses weak file permissions for (1) ppk files containing
private keys generated by puttygen and (2) session logs created by putty, which
allows local users to gain sensitive information by reading these files."
FE5+ seemingly affected.
As I stated via email, the NVD bug report is actually incorrect (I'd tell them
if I could find a good contact address); the bug only applies to putty < 0.59.
I've updated putty in FE5 and FE6 to 0.59-1, which takes care of the issue.
Thanks for the heads-up!