CVE-2026-6019

NameCVE-2026-6019
Descriptionhttp.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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
pypy3 (PTS)bullseye7.3.5+dfsg-2+deb11u2vulnerable
bullseye (security)7.3.5+dfsg-2+deb11u5vulnerable
bookworm7.3.11+dfsg-2+deb12u3vulnerable
trixie7.3.19+dfsg-2vulnerable
forky, sid7.3.21+dfsg-4vulnerable
python3.11 (PTS)bookworm3.11.2-6+deb12u6vulnerable
bookworm (security)3.11.2-6+deb12u3vulnerable
python3.13 (PTS)trixie3.13.5-2vulnerable
forky, sid3.13.12-1vulnerable
python3.14 (PTS)forky3.14.3-3vulnerable
sid3.14.4-2vulnerable
python3.9 (PTS)bullseye3.9.2-1vulnerable
bullseye (security)3.9.2-1+deb11u6vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
pypy3source(unstable)(unfixed)
python3.11source(unstable)(unfixed)
python3.13source(unstable)(unfixed)
python3.14source(unstable)(unfixed)
python3.9source(unstable)(unfixed)

Notes

https://mail.python.org/archives/list/security-announce@python.org/thread/IVNWGV2BBNC3RHQAFS22UP4DY56SAXX3/
https://github.com/python/cpython/issues/90309
https://github.com/python/cpython/pull/148848
https://github.com/python/cpython/commit/76b3923d688c0efc580658476c5f525ec8735104 (main)

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