Emails sent by pretix can utilize placeholders that will be filled with customer data. For example, when {name} is used in an email template, it will be replaced with the buyers name for the final email. This mechanism contained a security-relevant bug:
It was possible to exfiltrate information about the pretix system through specially crafted placeholder names such as {{event.init.code.co_filename}}. This way, an attacker with the ability to control email templates (usually every user of the pretix backend) could retrieve sensitive information from the system configuration, including even database passwords or API keys. pretix does include mechanisms to prevent the usage of such malicious placeholders, however due to a mistake in the code, they were not fully effective for this plugin.
Out of caution, we recommend that you rotate all passwords and API keys contained in your pretix.cfg file.
Weakness
In a language where the user can influence the name of a variable at runtime, if the variable names are not controlled, an attacker can read or write to arbitrary variables, or access arbitrary functions.