python-markdown2 through 2.3.8 allows XSS because element names are mishandled unless a \w+ match succeeds. For example, an attack might use elementname@ or elementname- with an onclick attribute.
{
"nvd_published_at": null,
"severity": "MODERATE",
"github_reviewed_at": "2020-04-22T19:19:38Z",
"github_reviewed": true,
"cwe_ids": [
"CWE-79"
]
}