CVE-2024-45800

Technical Description

Snappymail is an open source web-based email client. SnappyMail uses the `cleanHtml()` function to cleanup HTML and CSS in emails. Research discovered that the function has a few bugs which cause an mXSS exploit. Because the function allowed too many (invalid) HTML elements, it was possible (with incorrect markup) to trick the browser to "fix" the broken markup into valid markup. As a result a motivated attacker may be able to inject javascript. However, due to the default Content Security Policy the impact of the exploit is minimal. It could be possible to create an attack which leaks some data when loading images through the proxy.

This way it might be possible to use the proxy to attack the local system, like with `http://localhost:5000/leak`. Another attack could be to load a JavaScript attachment of the email. This is very tricky as the email must link to every possible UID as each email has a unique UID which has a value between 1 and 18446744073709551615 **v2.38.0** and up now r

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References