Using carefully crafted input, an attacker may be able to sneak arbitrary HTML and CSS through Sanitize >= 3.0.0, < 6.0.2 when Sanitize is configured to use the built-in "relaxed" config or when using a custom config that allows style elements and one or more CSS at-rules. This could result in XSS (cross-site scripting) or other undesired behavior when the malicious HTML and CSS are rendered in a browser.
Sanitize >= 6.0.2 performs additional escaping of CSS in style element content, which fixes this issue.
Users who are unable to upgrade can prevent this issue by using a Sanitize config that doesn't allow style elements, using a Sanitize config that doesn't allow CSS at-rules, or by manually escaping the character sequence </ as <\/ in style element content.
This issue was found by @cure53 during an audit of a project that uses Sanitize and was reported by one of that project's maintainers. Thank you!
{
"github_reviewed": true,
"cwe_ids": [
"CWE-79"
],
"github_reviewed_at": "2023-07-06T19:45:44Z",
"nvd_published_at": "2023-07-06T16:15:10Z",
"severity": "HIGH"
}