Contentful through 2020-05-21 for Python allows reflected XSS, as demonstrated by the api parameter to the-example-app.py.
{
"github_reviewed": true,
"severity": "MODERATE",
"github_reviewed_at": "2021-05-14T21:45:06Z",
"cwe_ids": [
"CWE-79"
],
"nvd_published_at": "2020-05-21T17:15:00Z"
}