{"id":"PSF-2026-21","details":"http.cookies.Morsel.js_output() returns an inline \u003cscript\u003e snippet and only escapes \" for JavaScript string context. It does not neutralize the HTML parser-sensitive sequence \u003c/script\u003e inside the generated script element. Mitigation base64-encodes the cookie value to disallow escaping using cookie value.","aliases":["BIT-libpython-2026-6019","BIT-python-2026-6019","BIT-python-min-2026-6019","CVE-2026-6019"],"modified":"2026-04-24T16:56:16.032973345Z","published":"2026-04-22T19:28:08.720Z","database_specific":{"cwe_ids":[]},"references":[{"type":"WEB","url":"https://github.com/python/cpython/pull/148848"},{"type":"REPORT","url":"https://github.com/python/cpython/issues/90309"},{"type":"ADVISORY","url":"https://mail.python.org/archives/list/security-announce@python.org/thread/IVNWGV2BBNC3RHQAFS22UP4DY56SAXX3/"},{"type":"FIX","url":"https://github.com/python/cpython/commit/76b3923d688c0efc580658476c5f525ec8735104"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/python/cpython","events":[{"introduced":"0"},{"fixed":"76b3923d688c0efc580658476c5f525ec8735104"}]}],"versions":["v0.9.8","v0.9.9","v1.0.1","v1.0.2","v1.1","v1.1.1","v1.2","v1.2b1","v1.2b2","v1.2b3","v1.2b4","v1.3","v1.3b1","v1.4","v1.4b1","v1.4b2","v1.4b3","v1.5","v1.5.1","v1.5.2","v1.5.2a1","v1.5.2a2","v1.5.2b1","v1.5.2b2","v1.5.2c1","v1.5a1","v1.5a2","v1.5a3","v1.5a4","v1.5b1","v1.5b2","v1.6a1","v1.6a2","v2.0","v2.0b1","v2.0b2","v2.0c1","v2.1","v2.1a1","v2.1a2","v2.1b1","v2.1b2","v2.1c1","v2.1c2","v2.2a3","v2.3c1","v2.3c2","v2.4","v2.4a1","v2.4a2","v2.4a3","v2.4b1","v2.4b2","v2.4c1","v3.0a1","v3.0a2","v3.0a3","v3.0a4","v3.0a5","v3.0b1","v3.0b2","v3.0b3","v3.0rc1","v3.0rc2","v3.0rc3","v3.1","v3.10.0a1","v3.10.0a7","v3.11.0a3","v3.11.0a4","v3.11.0a5","v3.11.0a6","v3.11.0a7","v3.11.0b1","v3.12.0a1","v3.12.0a2","v3.12.0a3","v3.12.0a4","v3.12.0a5","v3.12.0a6","v3.12.0a7","v3.12.0b1","v3.13.0a1","v3.13.0a2","v3.13.0a3","v3.13.0a4","v3.13.0a5","v3.13.0a6","v3.13.0b1","v3.14.0a1","v3.14.0a2","v3.14.0a3","v3.14.0a4","v3.14.0a5","v3.14.0a6","v3.14.0a7","v3.14.0b1","v3.15.0a1","v3.15.0a2","v3.15.0a3","v3.15.0a4","v3.15.0a5","v3.15.0a6","v3.15.0a7","v3.15.0a8","v3.1a1","v3.1a2","v3.1b1","v3.1rc1","v3.1rc2","v3.2a1","v3.2a2","v3.2a3","v3.2a4","v3.2b1","v3.2b2","v3.2rc1","v3.2rc2","v3.2rc3","v3.3.0a2","v3.3.0a3","v3.3.0a4","v3.3.0b1","v3.3.0b2","v3.3.0rc1","v3.3.0rc2","v3.3.0rc3","v3.4.0a1","v3.4.0a2","v3.4.0a3","v3.4.0a4","v3.4.0b1","v3.4.0b2","v3.4.0b3","v3.5.0a1","v3.5.0a2","v3.5.0a3","v3.5.0a4","v3.5.0b1","v3.6.0a3","v3.6.0b1","v3.7.0a2","v3.9.0a2"],"database_specific":{"source":"https://github.com/psf/advisory-database/blob/main/advisories/python/PSF-2026-21.json"}}],"schema_version":"1.7.5"}