CVE-2026-6019
BaseCookie.js_output() does not neutralize embedded characters
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.
INFO
Published Date :
April 22, 2026, 8:16 p.m.
Last Modified :
May 28, 2026, 7:15 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-6019
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | LOW | 28c92f92-d60d-412d-b760-e73465c3df22 | ||||
| CVSS 4.0 | LOW | [email protected] |
Solution
- Ensure cookie values are fully encoded.
- Implement robust output encoding for JavaScript strings.
- Neutralize HTML parser-sensitive sequences like </script>.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-6019.
| URL | Resource |
|---|---|
| https://github.com/python/cpython/commit/3c59b8b53fc75c7f9578d16fb8201ceb43e8f76c | Patch |
| https://github.com/python/cpython/commit/76b3923d688c0efc580658476c5f525ec8735104 | Patch |
| https://github.com/python/cpython/commit/f795e042043dfe26c42e1971d4502c1cdc4c65b8 | Patch |
| https://github.com/python/cpython/issues/90309 | Exploit Issue Tracking |
| https://github.com/python/cpython/pull/148848 | Issue Tracking Patch |
| https://mail.python.org/archives/list/[email protected]/thread/IVNWGV2BBNC3RHQAFS22UP4DY56SAXX3/ | Mailing List Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-6019 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-6019
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-6019 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-6019 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Reanalysis by [email protected]
May. 28, 2026
Action Type Old Value New Value Changed CPE Configuration OR *cpe:2.3:a:python:cpython:*:*:*:*:*:*:*:* versions up to (excluding) 3.15.0 OR *cpe:2.3:a:python:python:*:*:*:*:*:*:*:* versions up to (excluding) 3.15.0 -
Initial Analysis by [email protected]
May. 18, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Added CWE CWE-116 Added CPE Configuration OR *cpe:2.3:a:python:cpython:*:*:*:*:*:*:*:* versions up to (excluding) 3.15.0 Added Reference Type Python Software Foundation: https://github.com/python/cpython/commit/3c59b8b53fc75c7f9578d16fb8201ceb43e8f76c Types: Patch Added Reference Type Python Software Foundation: https://github.com/python/cpython/commit/76b3923d688c0efc580658476c5f525ec8735104 Types: Patch Added Reference Type Python Software Foundation: https://github.com/python/cpython/commit/f795e042043dfe26c42e1971d4502c1cdc4c65b8 Types: Patch Added Reference Type Python Software Foundation: https://github.com/python/cpython/issues/90309 Types: Exploit, Issue Tracking Added Reference Type Python Software Foundation: https://github.com/python/cpython/pull/148848 Types: Issue Tracking, Patch Added Reference Type Python Software Foundation: https://mail.python.org/archives/list/[email protected]/thread/IVNWGV2BBNC3RHQAFS22UP4DY56SAXX3/ Types: Mailing List, Vendor Advisory -
CVE Modified by [email protected]
Apr. 29, 2026
Action Type Old Value New Value Added Reference https://github.com/python/cpython/commit/3c59b8b53fc75c7f9578d16fb8201ceb43e8f76c Added Reference https://github.com/python/cpython/commit/f795e042043dfe26c42e1971d4502c1cdc4c65b8 -
New CVE Received by [email protected]
Apr. 22, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-150 Added Reference https://github.com/python/cpython/commit/76b3923d688c0efc580658476c5f525ec8735104 Added Reference https://github.com/python/cpython/issues/90309 Added Reference https://github.com/python/cpython/pull/148848 Added Reference https://mail.python.org/archives/list/[email protected]/thread/IVNWGV2BBNC3RHQAFS22UP4DY56SAXX3/