Impact
Through the store-api it is possible as a attacker to check if a specific e-mail address has an account in the shop.
Using the store-api endpoint /store-api/account/recovery-password you get the response
{"errors":[{"status":"404","code":"CHECKOUT__CUSTOMER_NOT_FOUND","title":"Not Found","detail":"No matching customer for the email \u0022asdasfd@asdads.de\u0022 was found.","meta":{"parameters":{"email":"asdasfd@asdads.de"}}}]}
which indicates clearly that there is no account for this customer. In contrast you get a success response if the account was found.
Patches
Update to Shopware 6.6.10.3
Workarounds
For older versions of 6.5 or 6.4, corresponding security measures are also available via a plugin. For the full range of functions, we recommend updating to the latest Shopware version.