CVE-2026-6019

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.

EPSS — Exploit Prediction

0.0003

Probability of exploitation

0.08%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-150 CWE-150

References

Other References

https://github.com/python/cpython/commit/3c59b8b53fc75c7f9578d16fb8201ceb43e8f76c https://github.com/python/cpython/commit/76b3923d688c0efc580658476c5f525ec8735104 https://github.com/python/cpython/commit/f795e042043dfe26c42e1971d4502c1cdc4c65b8 https://github.com/python/cpython/issues/90309 https://github.com/python/cpython/pull/148848 https://mail.python.org/archives/list/[email protected]/thread/IVNWGV2BBNC3RHQAFS22UP4DY56SAXX3/

Frequently Asked Questions

What is CVE-2026-6019? +

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.

How do I check if I'm vulnerable to CVE-2026-6019? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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