Medium severity · published Apr 22, 2026
CVE-2026-6019
BaseCookie.js_output() does not neutralize embedded characters
6.1
CVSS
0.2%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 11% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CP
CPython · Python Software Foundation
before 3.13.14; 3.14.0a1 before 3.14.5rc1; 3.15.0a1 before 3.15.0b1 · source: vendor
PY
Python · Python
before 3.13.14; 3.14.0 through 3.14.4; 3.15.0; 3.15.0; 3.15.0; 3.15.0; +4 more · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-6019
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-6019
Patch
https://github.com/python/cpython/commit/3c59b8b53fc75c7f9578d16fb8201ceb43e8f76c
Patch
https://github.com/python/cpython/commit/76b3923d688c0efc580658476c5f525ec8735104
Patch
https://github.com/python/cpython/commit/f795e042043dfe26c42e1971d4502c1cdc4c65b8
Exploit
https://github.com/python/cpython/issues/90309
Issue Tracking
https://github.com/python/cpython/pull/148848
Mailing List
https://mail.python.org/archives/list/security-announce@python.org/thread/IVNWGV2BBNC3RHQAFS22UP4DY56SAXX3/
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