CVE-2026-6019: http.cookies.Morsel.js_output() returns an inline <script> snippet and only escapes " for JavaScript string co

Routine

MEDIUM 6.1UPGRADE

CVE-2026-6019 is a medium-severity flaw (CVSS 6.1) affecting python. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 89%)
CISA exploited list	No
Weakness	CWE-150, CWE-116
Published	2026-04-22
Last modified	2026-10-26

Publisher (CNA): Python Software Foundation · Vendor: python

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-22 20:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

python python UPGRADE

Affected: < 3.13.14 · >= 3.14.0 and <= 3.14.4 · 3.15.0 alpha1 · 3.15.0 alpha2 · 3.15.0 alpha3 · 3.15.0 alpha4 · 3.15.0 alpha5 · 3.15.0 alpha6

Fixed in: 3.13.14

Safe to downgrade to: a release before 3.14.0

1. Check installed version

apt-cache policy python || rpm -q python || python --version

2. UPGRADE to 3.13.14 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade python

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade python

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 3.14.0 (Debian / Ubuntu)

apt-cache madison python sudo apt install python=<VERSION_BEFORE_3.14.0> sudo apt-mark hold python

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list python sudo dnf downgrade python-<VERSION_BEFORE_3.14.0> sudo dnf versionlock add python

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Advisories and coverage

Official advisories

AlmaLinux Errata: [ALSA-2026:28247] Important: python3.14 security, bug fix, and enhancement update 2026-06-25

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-6019?

python: upgrade to 3.13.14. Exact commands for each OS are on this page.

Is CVE-2026-6019 being exploited?

CVE-2026-6019 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-6019 affect?

CVE-2026-6019 affects python. Severity is medium (CVSS 6.1). 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-

How urgent is CVE-2026-6019?

Priority 29/100. Public exploit reference

Software pages

Python vulnerabilities

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References

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