Our CGLIB 3.2 upgrade only happened in 4.2.3, so I'm afraid that any further upgrades are bound to 4.2.x and higher. 4.2.5 is scheduled for Feb 18 which is a bit tight; if CGLIB 3.2.1 won't be released in time for that, the next opportunity will be 4.2.6 in early May.
Please note that there won't be any further 4.1.x releases in any case; 4.1.9 in December was the last one in that branch. We expect everybody to upgrade to 4.2.5+ from there. Likewise, 4.2.9 will be released in late 2016, with us expecting everybody to upgrade to 4.3.x from there.
Stéphane Nicoll, according to the release request on GitHub, the CGLIB 3.2.1 release is imminent, so let's aim for getting it repackaged into 4.2.5... even if it means delaying our release for a few days. Aiming for Feb 22 at the moment, just in time for Boot 1.3.3 / 1.4.0 M1.
It looks like the CGLIB won't be happening in time, due to API compatibility concerns (cglib/cglib#61 (comment)), and we're not going to delay beyond Feb 22 on our end. Scheduling for 4.3 instead; it remains to be seen whether we can backport this to a later 4.2.x release but it can certainly make 4.3 at least.