There is a LOW severity vulnerability affecting CPython.

http.cookies.Morsel.js_output() returns an inline <script> snippet and only escapes " for JavaScript string context. It does not neutralize the HTML parser-sensitive sequence </script> inside the generated script element. Mitigation base64-encodes the cookie value to disallow escaping using cookie value.

Please see the linked CVE ID for the latest information on affected versions:

• https://www.cve.org/CVERecord?id=CVE-2026-6019
• https://github.com/python/cpython/pull/148848