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CVE-2026-6658

Cross-site Scripting (XSS) in jupyter/nbconvert

5.4 MediumFix available

A vulnerability in jupyter/nbconvert versions <= 7.17.0 allows for Cross-site Scripting (XSS) via unsanitized text/vnd.mermaid output in HTML exports. The data_mermaid block in share/templates/lab/base.html.j2 renders text/vnd.mermaid cell output directly into HTML without escaping, enabling attackers to inject arbitrary HTML/JavaScript by breaking out of the <pre> tag. This vulnerability impacts any server using nbconvert to render notebooks as HTML, allowing attackers to execute arbitrary JavaScript in the context of users viewing the HTML export.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
Required

What an attacker can affect

Confidentiality
Low
Integrity
Low
Availability
None

Exploit likelihood

0.16%Down 0.1 points since Jun 26, 2026
90%50%10%1%

What each source reports

CVE List Score used 5.4

Cross-site Scripting (XSS) in jupyter/nbconvert

A vulnerability in jupyter/nbconvert versions <= 7.17.0 allows for Cross-site Scripting (XSS) via unsanitized text/vnd.mermaid output in HTML exports. The data_mermaid block in share/templates/lab/base.html.j2 renders text/vnd.mermaid cell output directly into HTML without escaping, enabling attackers to inject arbitrary HTML/JavaScript by breaking out of the <pre> tag. This vulnerability impacts any server using nbconvert to render notebooks as HTML, allowing attackers to execute arbitrary JavaScript in the context of users viewing the HTML export.

Record
CVE-2026-6658
CVSS 3.0
5.4 MediumCVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Weakness
CWE-79
Updated
2026-11-02
EUVDEUVD-2026-39642 5.4

A vulnerability in jupyter/nbconvert versions <= 7.17.0 allows for Cross-site Scripting (XSS) via unsanitized text/vnd.mermaid output in HTML exports. The data_mermaid block in share/templates/lab/base.html.j2 renders text/vnd.mermaid cell output directly into HTML without escaping, enabling attackers to inject arbitrary HTML/JavaScript by breaking out of the <pre> tag. This vulnerability impacts any server using nbconvert to render notebooks as HTML, allowing attackers to execute arbitrary JavaScript in the context of users viewing the HTML export.

Record
EUVD-2026-39642
CVSS 3.0
5.4 MediumCVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-9754-6rhw-gj3h 5.4

jupyter/nbconvert allows Cross-site Scripting (XSS) via unsanitized `text/vnd.mermaid` output in HTML exports

A vulnerability in jupyter/nbconvert versions <= 7.17.0 allows for Cross-site Scripting (XSS) via unsanitized text/vnd.mermaid output in HTML exports. The data_mermaid block in share/templates/lab/base.html.j2 renders text/vnd.mermaid cell output directly into HTML without escaping, enabling attackers to inject arbitrary HTML/JavaScript by breaking out of the <pre> tag. This vulnerability impacts any server using nbconvert to render notebooks as HTML, allowing attackers to execute arbitrary JavaScript in the context of users viewing the HTML export.

Record
GHSA-9754-6rhw-gj3h
CVSS 3.0
5.4 MediumCVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Weakness
CWE-79
Updated
2026-11-06
NVD 5.4

A vulnerability in jupyter/nbconvert versions <= 7.17.0 allows for Cross-site Scripting (XSS) via unsanitized text/vnd.mermaid output in HTML exports. The data_mermaid block in share/templates/lab/base.html.j2 renders text/vnd.mermaid cell output directly into HTML without escaping, enabling attackers to inject arbitrary HTML/JavaScript by breaking out of the <pre> tag. This vulnerability impacts any server using nbconvert to render notebooks as HTML, allowing attackers to execute arbitrary JavaScript in the context of users viewing the HTML export.

Record
CVE-2026-6658
CVSS 3.0
5.4 MediumCVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Weakness
CWE-79
Updated
2026-11-02
OSVDEBIAN-CVE-2026-6658 5.4

A vulnerability in jupyter/nbconvert versions <= 7.17.0 allows for Cross-site Scripting (XSS) via unsanitized text/vnd.mermaid output in HTML exports. The data_mermaid block in share/templates/lab/base.html.j2 renders text/vnd.mermaid cell output directly into HTML without escaping, enabling attackers to inject arbitrary HTML/JavaScript by breaking out of the <pre> tag. This vulnerability impacts any server using nbconvert to render notebooks as HTML, allowing attackers to execute arbitrary JavaScript in the context of users viewing the HTML export.

Record
DEBIAN-CVE-2026-6658
CVSS 3.0
5.4 MediumCVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
OSVGHSA-9754-6rhw-gj3h 5.4

jupyter/nbconvert allows Cross-site Scripting (XSS) via unsanitized `text/vnd.mermaid` output in HTML exports

A vulnerability in jupyter/nbconvert versions <= 7.17.0 allows for Cross-site Scripting (XSS) via unsanitized text/vnd.mermaid output in HTML exports. The data_mermaid block in share/templates/lab/base.html.j2 renders text/vnd.mermaid cell output directly into HTML without escaping, enabling attackers to inject arbitrary HTML/JavaScript by breaking out of the <pre> tag. This vulnerability impacts any server using nbconvert to render notebooks as HTML, allowing attackers to execute arbitrary JavaScript in the context of users viewing the HTML export.

Record
GHSA-9754-6rhw-gj3h
CVSS 3.0
5.4 MediumCVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Weakness
CWE-79
Updated
2026-11-06
OSVUBUNTU-CVE-2026-6658 5.4

A vulnerability in jupyter/nbconvert versions <= 7.17.0 allows for Cross-site Scripting (XSS) via unsanitized text/vnd.mermaid output in HTML exports. The data_mermaid block in share/templates/lab/base.html.j2 renders text/vnd.mermaid cell output directly into HTML without escaping, enabling attackers to inject arbitrary HTML/JavaScript by breaking out of the <pre> tag. This vulnerability impacts any server using nbconvert to render notebooks as HTML, allowing attackers to execute arbitrary JavaScript in the context of users viewing the HTML export.

Record
UBUNTU-CVE-2026-6658
CVSS 3.0
5.4 MediumCVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
OSVopenSUSE-SU-2026:11725-1 No score

jupyter-nbconvert-7.17.1-2.1 on GA media

These are all security issues fixed in the jupyter-nbconvert-7.17.1-2.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:11725-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
nbconvert
PyPI
 through 7.17.0 None known
nbconvert
Debian:12
 All versions, plus listed versions
6.5.3-36.5.3-46.5.3-57.16.4-17.16.4-2
Show 5 moreShow less
7.16.5-17.16.6-17.17.0-17.17.1-17.17.1-2
 None known
nbconvert
Debian:13
 All versions, plus listed versions
7.16.6-17.16.6-1+deb13u17.17.0-17.17.1-17.17.1-2
 None known
nbconvert
Debian:14
 All versions, plus listed versions
7.16.6-17.17.0-17.17.1-17.17.1-2
 None known
nbconvert
PyPI
 through 7.17.0, plus listed versions
0.0.04.0.04.1.04.2.04.3.0
Show 45 moreShow less
5.0.05.0.0b15.1.05.1.15.2.15.3.05.3.15.4.05.4.15.4.1.dev05.5.05.6.05.6.16.0.06.0.0a06.0.0a16.0.0a26.0.0a36.0.0a46.0.0a56.0.0a66.0.0b76.0.0rc06.0.16.0.26.0.36.0.46.0.56.0.66.0.76.1.06.1.0rc06.1.1b06.2.06.2.0rc06.2.0rc16.2.0rc26.3.06.3.0b06.4.06.4.16.4.26.4.36.4.46.4.5
 None known
nbconvert
Ubuntu:18.04:LTS
 All versions, plus listed versions
4.2.0-45.3.1-1
 None known
nbconvert
Ubuntu:20.04:LTS
 All versions, plus listed versions
5.4-2ubuntu25.6.0-15.6.0-25.6.1-1
 None known
nbconvert
Ubuntu:22.04:LTS
 All versions, plus listed versions
5.6.1-36.1.0-16.3.0-16.4.0-1
 None known
nbconvert
Ubuntu:24.04:LTS
 All versions, plus listed versions
6.5.3-46.5.3-5
 None known
nbconvert
Ubuntu:25.10
 All versions, plus listed versions
7.16.6-1
 None known
nbconvert
Ubuntu:26.10
 All versions, plus listed versions
7.17.0-17.17.1-2
 None known
nbconvert
Ubuntu:26.04:LTS
 All versions, plus listed versions
7.16.6-17.17.0-1
 None known
python-nbconvert
openSUSE:Tumbleweed
 before 7.17.1-2.1
7.17.1-2.1

History

History
RecordedChangedSources
affected, referencesOSV
affected, factsGitHub Advisories
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-6658 is a medium vulnerability (CVSS 5.4) in Jupyter Jupyter/jupyter, published June 26, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.16%, the 5th percentile. Fixed in python-nbconvert 7.17.1-2.1.

References

This page doesn't list everything

Left out here: 52 versions. The JSON record has them.

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