can't specify empty username/password to ldap server

### I did this I'm using curl to download CRL for x.509 certificates like follows. $ curl-8.20.0 -u : 'ldap://ldap.example.com/o=xxx,c=xxx?certificateRevocationList' >CRL.ldif This method work fine with curl-8.20.0 or prior (except for early curl-8.19.0), but does not curl-8.21.0. $ curl-8.21.0 -u : 'ldap://ldap.example.com/o=xxx,c=xxx?certificateRevocationList' >CRL.ldif curl: (38) LDAP local: bind via ldap_win_bind 資格情報が無効です <-- Invalid credentials I also tried below, but does not work as well. $ curl-8.21.0 'ldap://:@ldap.example.com/o=xxx,c=xxx?certificateRevocationList' >CRL.ldif curl: (38) LDAP local: bind via ldap_win_bind 資格情報が無効です <-- Invalid credentials ### I expected the following I want to specify empty username/password to ldap server using curl. ### curl/libcurl version curl 8.21.0 (x86_64-w64-mingw32) libcurl/8.21.0 LibreSSL/4.3.2 zlib/1.3.1.zlib-ng brotli/1.2.0 zstd/1.5.7 WinIDN libpsl/0.21.5 libssh2/1.11.1 nghttp2/1.69.0 ngtcp2/1.23.0 nghttp3/1.16.0 WinLDAP Release-Date: 2026-06-24 ### operating system Windows 11 Pro 25H2