CVE-2026-6019

MEDIUM severity · CVSS 6.1 · CWE-150

6.1CVSS MEDIUM

Summary

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.

Impact & exploitability

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionRequired

Confidentiality impactLow

Integrity impactLow

Availability impactNone

Exploit probability (EPSS)0%

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected products we track (1)

Python

Recommendation

Apply the vendor fix in your normal patch cycle. Open any affected product above for its exact safe version.

Official patch: https://github.com/python/cpython/commit/3c59b8b53fc75c7f9578d16fb8201ceb43e8f76c ↗

Additional information

NVD record
https://github.com/python/cpython/commit/3c59b8b53fc75c7f9578d16fb8201ceb43e8f76cPatch
https://github.com/python/cpython/commit/76b3923d688c0efc580658476c5f525ec8735104Patch
https://github.com/python/cpython/commit/f795e042043dfe26c42e1971d4502c1cdc4c65b8Patch
https://github.com/python/cpython/pull/148848Patch
https://mail.python.org/archives/list/security-announce@python.org/thread/IVNWGV2BBNC3RHQAFS22UP4DY56SAXX3/Advisory
https://github.com/python/cpython/issues/90309Exploit