This vulnerability was an Information Disclosure vulnerability in the WAVLINK WN530H4 router.
There was sensitive information disclosure located at the endpoint /cgi-bin/ExportAllSettings.sh. In this information disclosure, an attacker could download all of the router settings, and even gain access to the username and password that is set.
The file was a key-value pair with all of the router settings. This seemed to be an intended feature from the router developers, however, the authentication bypass vulnerability caused this endpoint to be exposed. While the information disclosure was only possible due to incorrect access controls, information (such as cleartext passwords) was exposed that should have been better protected.
Here is a sample of the data returned by that endpoint:
#The following line must not be removed.
##RT2860CONF
Default
WebInit=1
LOGO1=images/WAVLINK-logo.png
LOGO2=images/WAVLINK-logo.gif
HostName=WAVLINK
Login=admin2860
Password=Cerne123!
Login_def=admin
Password_def=admin
...omitted for brevity...References: NVD entry for CVE-2020-12127