CVE-2024-45800 Multiple mXSS found in snappymail HTML parser
Attackers can inject JavaScript via malformed HTML in emails, potentially leading to code execution or data leakage through proxy requests.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2024-45800?
CVE-2024-45800 is a medium-severity cross-site scripting vulnerability in the-djmaze snappymail, published on 16 Sep 2024. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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 remove unsupported HTML elements which mitigates the issue. Users are advised to upgrade. Older versions can install an extension named "Security mXSS" as a mitigation. This will be available at the administration area at `/?admin#/packages`. **NOTE:** this extension can not "fix" malicious code in encrypted messages or (html) attachments as it can't manipulate the JavaScript code for this. It only protects normal message HTML.
Weakness: CWE-79
Which versions are affected by CVE-2024-45800?
How do I fix CVE-2024-45800?
No fix has been published for CVE-2024-45800 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2024-45800 being exploited?
There is no known exploitation of CVE-2024-45800 in the wild and no public exploit code.
Sources
Also known as GHSA-2rq7-79vp-ffxm.