これに引っかかちゃってるクライアントがけっこうあるってことなのかしらね…
> * "DST Root CA X3" is about to expire, however it has issued an updated cross-signature to letsencrypt beyond its own expiry
> * This causes issues with older implementations of openssl & gnutls that reject such chains when offered to clients by servers.
https://bugs.launchpad.net/ubuntu/+source/ca-certificates/+bug/1944481
bugs.launchpad.netBug #1944481 “Distrust “DST Root CA X3"" : Bugs : ca-certificates package : Ubuntu[Impact]
* ca-certificates trusts the letsencrypt CA certificate "ISRG Root X1"
* ca-certificates also trusts the CA certificate "DST Root CA X3" which cross-signs letencrypt CA
* "DST Root CA X3" is about to expire, however it has issued an updated cross-signature to letsencrypt beyond its own expiry
* This causes issues with older implementations of openssl & gnutls that reject such chains when offered to clients by servers.
* We have provided fixes for openssl in xenial and gnutls in...