Medium · published October 17, 2023
In dotCMS, versions mentioned, a flaw in the NormalizationFilter does not strip double slashes (//) from URLs, potentially enabling bypasses for XSS and access controls. An example affected URL is https://demo.dotcms.com//html/portlet/ext/files/edit_text_inc.jsp , which should return a 404 response but didn't.
The oversight in the default invalid URL character list can be viewed at the provided GitHub link https://github.com/dotCMS/core/blob/master/dotCMS/src/main/java/com/dotcms/filters/NormalizationFilter.java#L37 .
To mitigate, users can block URLs with double slashes at firewalls or utilize dotCMS config variables.
Specifically, they can use the DOT_URI_NORMALIZATION_FORBIDDEN_STRINGS environmental variable to add // to the list of invalid strings.
Additionally, the DOT_URI_NORMALIZATION_FORBIDDEN_REGEX variable offers more detailed control, for instance, to block //html.* URLs.
Fix Version:23.06+, LTS 22.03.7+, LTS 23.01.4+