# CVE-2021-32862: nbconvert vulnerable to cross-site scripting (XSS) via multiple exploit paths

> Attackers can inject arbitrary HTML into Jupyter notebooks converted to HTML, leading to cross-site scripting when served by web servers.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Aug 2022
- **Updated:** 2 Sep 2024
- **Also known as:** DEBIAN-CVE-2021-32862, DLA-3442-1, DLA-3863-1, GHSA-9jmq-rx5f-8jwq, GHSA-h274-fcvj-h2wm, PYSEC-2022-249, UBUNTU-CVE-2021-32862

## What is CVE-2021-32862?

CVE-2021-32862 is a high-severity cross-site scripting vulnerability in Debian Debian Linux, published on 18 Aug 2022. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

The GitHub Security Lab discovered sixteen ways to exploit a cross-site scripting vulnerability in nbconvert. When using nbconvert to generate an HTML version of a user-controllable notebook, it is possible to inject arbitrary HTML which may lead to cross-site scripting (XSS) vulnerabilities if these HTML notebooks are served by a web server (eg: nbviewer).

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2021-32862?

3 open source packages ship an affected version, including nbconvert. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `nbconvert` | PyPI | All versions | 6.3.0a0 |
| `nbconvert` | PyPI | All versions | 6.5.1 |
| `nbconvert` | PyPI | All versions | 6.5.1 |

Products: Debian Debian Linux, Jupyter Nbconvert.

## How do I fix CVE-2021-32862?

Upgrade nbconvert to a fixed version for your release line: 6.3.0a0 or 6.5.1.

## Is CVE-2021-32862 being exploited?

There is no known exploitation of CVE-2021-32862 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-32862 and fix it if it is affected.

What it is: CVE-2021-32862 is a high-severity cross-site scripting vulnerability in Debian Debian Linux, published on 18 Aug 2022. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-32862 in the wild and no public exploit code.

Affected packages and fixed versions:
- nbconvert (PyPI): affected all versions; fixed in 6.3.0a0
- nbconvert (PyPI): affected all versions; fixed in 6.5.1
- nbconvert (PyPI): affected all versions; fixed in 6.5.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-32862/ (Markdown: https://insights.sbomify.com/CVE-2021-32862/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32862
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32862
- OSV: https://osv.dev/vulnerability/CVE-2021-32862

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-32862/
Summaries are generated and may contain mistakes; the official description above is the record.