CVE-2020-4070 Cross-site Scripting in CSS Validator
An attacker can execute arbitrary scripts in a victim's browser by tricking them into clicking a crafted link in the W3C CSS Validator.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2020-4070?
CVE-2020-4070 is a medium-severity cross-site scripting vulnerability in World Wide Web Consortium (W3C) CSS Validator, published on 22 Jun 2020. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
In CSS Validator less than or equal to commit 54d68a1, there is a cross-site scripting vulnerability in handling URIs. A user would have to click on a specifically crafted validator link to trigger it. This has been patched in commit e5c09a9.
Weakness: CWE-79
Which versions are affected by CVE-2020-4070?
It affects 1 product.
Products include W3c Css Validator.
How do I fix CVE-2020-4070?
No fix has been published for CVE-2020-4070 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-2020-4070 being exploited?
There is no known exploitation of CVE-2020-4070 in the wild and no public exploit code.
Sources
Also known as GHSA-wf36-7w73-rh8c.