Is it know if zimbra has any binary files that have statically linked glibc or will updating the host catch all the links to the system glibc?
I've checked nginx and postfix and both of them seems to be using system:
$ ldd /opt/zimbra/nginx/sbin/nginx |grep "libc."
libc.so.6 => /lib64/libc.so.6 (0x00007f12deda2000)
$ ldd /opt/zimbra/postfix/sbin/postfix |grep "libc."
libc.so.6 => /lib64/libc.so.6 (0x00007fc3f9e0e000)