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Fencer Vulns
medium 6.1

CVE-2026-6019 json

BaseCookie.js_output() does not neutralize embedded characters

published 2026-04-22 6 mo ago modified 2026-10-26 13 d ago also BIT-libpython-2026-6019 , BIT-python-2026-6019 , BIT-python-min-2026-6019 , EUVD-2026-25079

cvss
6.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 11%
public exploits
0
none known

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.

Patch / fix

  • bitnami libpython 3.13.14, 3.14.5
  • bitnami python 3.13.14, 3.14.5
  • bitnami python-min 3.13.14, 3.14.5
  • Python Software Foundation CPython 3.13.14, 3.14.5rc1, 3.15.0b1
  • python3.11 Debian 12 3.11.2-6+deb12u9
  • python3.13 Debian 13 3.13.5-2+deb13u2
  • python3.14 Debian 14 3.14.5~rc1-1

debian advisories DEBIAN-CVE-2026-6019

  • python3.10 Ubuntu 22.04 LTS 3.10.12-1~22.04.16
  • python3.12 Ubuntu 24.04 LTS 3.12.3-1ubuntu0.15
  • python3.14 Ubuntu 26.04 LTS 3.14.4-1ubuntu0.1
  • python2.7 Ubuntu Pro 14.04 LTS 2.7.6-8ubuntu0.6+esm30
  • python2.7 Ubuntu Pro 16.04 LTS 2.7.12-1ubuntu0~16.04.18+esm22
  • python2.7 Ubuntu Pro 18.04 LTS 2.7.17-1~18.04ubuntu1.13+esm15
  • python2.7 Ubuntu Pro 22.04 LTS 2.7.18-13ubuntu1.5+esm9
  • python3.4 Ubuntu Pro 14.04 LTS 3.4.3-1ubuntu1~14.04.7+esm21

ubuntu advisories UBUNTU-CVE-2026-6019

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • python3.12 hummingbird 1 3.12.14-1.hum1
  • python3.12-idle hummingbird 1 3.12.14-1.hum1
  • python3.12-libs hummingbird 1 3.12.14-1.hum1
  • python3.12-test hummingbird 1 3.12.14-1.hum1
  • python3.12-tkinter hummingbird 1 3.12.14-1.hum1
  • python3.11 hummingbird 1 3.11.16-1.hum1
  • python3.11-idle hummingbird 1 3.11.16-1.hum1
  • python3.11-libs hummingbird 1 3.11.16-1.hum1

red hat advisories RHSA-2026:58420RHSA-2026:57660RHSA-2026:33885RHSA-2026:32997RHSA-2026:32980RHSA-2026:28581

  • python3 SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +11 more 3.6.15-150300.10.129.1
  • python3-core SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +12 more 3.6.15-150300.10.129.1
  • grafana Multi Linux Manager Tools SLE-15 12.4.10-150002.4.27.1
  • mgr-push Multi Linux Manager Tools SLE-15 5.2.5-150002.3.12.1
  • spacecmd Multi Linux Manager Tools SLE-15 5.2.10-150002.3.15.1
  • uyuni-tools Multi Linux Manager Tools SLE-Micro-5, Multi Linux Manager Tools SLE-15 5.2.17-150002.3.20.1
  • venv-salt-minion Multi Linux Manager Tools SLE-Micro-5, Multi Linux Manager Tools SLE-15 3006.0-150002.5.22.1
  • spacewalk-client-tools Multi Linux Manager Tools SLE-15 5.2.7-150002.3.12.1

suse advisories SUSE-SU-2026:4754-1SUSE-SU-2026:4585-1SUSE-SU-2026:4584-1SUSE-SU-2026:4583-1SUSE-SU-2026:4582-1SUSE-SU-2026:4581-1

  • python3 openSUSE Leap 16.0 3.13.14-160000.1.1
  • python313 openSUSE Leap 16.0 3.13.14-160000.1.1
  • python313-core openSUSE Leap 16.0 3.13.14-160000.1.1
  • python313-nogil openSUSE Leap 16.0 3.13.14-160000.1.1
  • python313-documentation openSUSE Leap 16.0 3.13.14-160000.1.1
  • python313-nogil-nogil-core openSUSE Leap 16.0 3.13.14-160000.1.1
  • python314 openSUSE Tumbleweed 3.14.6-1.1
  • python312 openSUSE Tumbleweed 3.12.13-6.1

opensuse advisories openSUSE-SU-2026:21459-1openSUSE-SU-2026:11181-1openSUSE-SU-2026:11100-1openSUSE-SU-2026:11068-1openSUSE-SU-2026:10667-1openSUSE-SU-2026:10647-1

  • python3.14 AlmaLinux 9 3.14.5-1.el9_8
  • python3.14-idle AlmaLinux 9 3.14.5-1.el9_8
  • python3.14-libs AlmaLinux 9 3.14.5-1.el9_8
  • python3.14-test AlmaLinux 9 3.14.5-1.el9_8
  • python3.14-tkinter AlmaLinux 9 3.14.5-1.el9_8
  • python3.14-freethreading AlmaLinux 9 3.14.5-1.el9_8
  • python3.14-freethreading-idle AlmaLinux 9 3.14.5-1.el9_8
  • python3.14-freethreading-libs AlmaLinux 9 3.14.5-1.el9_8

almalinux advisories ALSA-2026:28247ALSA-2026:28581

  • python3.14 Rocky Linux 10 3.14.5-1.el10_2
  • python3.14 Rocky Linux 9 3.14.5-1.el9_8

rocky linux advisories RLSA-2026:28581RLSA-2026:28247

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-6019 updated cvss 6.8

python: Python: Cross-Site Scripting (XSS) vulnerability in http.cookies module

  • Red Hat Enterprise Linux 6 python, tkinter, python-libs, python-test, python-tools Red Hat Enterprise Linux 7 python, python3, tkinter, python-libs, python-test, python-tools, +4 more Red Hat Enterprise Linux 8 numpy, scipy, PyYAML, python3, mod_wsgi, python36, +89 more Red Hat Enterprise Linux 9 python3, python3.9, python3.11, python3.12, python3-idle, python3-libs, +11 more Red Hat Enterprise Linux 10 python3.12 Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-cuda-rhel9, rhelai3/bootc-rocm-rhel9, rhelai3/bootc-aws-cuda-rhel9, rhelai3/bootc-gcp-cuda-rhel9, rhelai3/bootc-azure-cuda-rhel9, rhelai3/bootc-azure-rocm-rhel9
    +2 more products
    Red Hat OpenShift AI (RHOAI) rhoai/odh-workbench-codeserver-datascience-cpu-py312-rhel9 Red Hat OpenShift Dev Spaces devspaces/code-rhel9, devspaces/pluginregistry-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux AppStream (v. 9) python3.14 3.14.5-1.el9_8, python3.14-libs 3.14.5-1.el9_8, python3.14-tkinter 3.14.5-1.el9_8
    fixed: vendor fix RHSA-2026:28247
  • Red Hat Enterprise Linux AppStream (v. 10) python3.14 3.14.5-1.el10_2, python3.14-libs 3.14.5-1.el10_2, python3.14-tkinter 3.14.5-1.el10_2
    fixed: vendor fix RHSA-2026:28581
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) python3.14 3.14.5-1.el9_8, python3.14-idle 3.14.5-1.el9_8, python3.14-test 3.14.5-1.el9_8, python3.14-tkinter 3.14.5-1.el9_8, python3.14-freethreading 3.14.5-1.el9_8, python3.14-freethreading-idle 3.14.5-1.el9_8, +3 more
    fixed: vendor fix RHSA-2026:28247
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) python3.14-idle 3.14.5-1.el10_2, python3.14-test 3.14.5-1.el10_2, python3.14-freethreading 3.14.5-1.el10_2, python3.14-freethreading-idle 3.14.5-1.el10_2, python3.14-freethreading-libs 3.14.5-1.el10_2, python3.14-freethreading-test 3.14.5-1.el10_2, +1 more
    fixed: vendor fix RHSA-2026:28581
  • Red Hat Hardened Images python3 3.14.5-2.hum1, python3.14 3.14.5-2.hum1, python3.11 3.11.16-1.hum1, python3.12 3.12.14-1.hum1, python3-idle 3.14.5-2.hum1, python3-libs 3.14.5-2.hum1, +32 more
    fixed: vendor fix RHSA-2026:22952

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
6 mo ago

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/python/cpython/issues/90309 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 2.1 CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
CNA 4.0 2.1 CVSS:4.0/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
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
OSV 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
bitnami libpython
<3.13.14
>=3.14.0, <3.14.5
3.13.14
3.14.5
bitnami python
<3.13.14
>=3.14.0, <3.14.5
3.13.14
3.14.5
bitnami python-min
<3.13.14
>=3.14.0, <3.14.5
3.13.14
3.14.5

Affected products

  • Python Software Foundation CPython

Classification

Weakness
  • CWE-150 Improper Neutralization of Escape, Meta, or Control Sequences
  • CWE-116 Improper Encoding or Escaping of Output

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.