# CVE-2021-32561: OctoPrint API Error Messages vulnerable to XSS

> Attackers can execute arbitrary scripts in the OctoPrint web interface via reflected XSS in API error messages.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 11 May 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-vcx4-fpmp-mvv6, PYSEC-2021-30

## What is CVE-2021-32561?

CVE-2021-32561 is a medium-severity cross-site scripting vulnerability in n/a, published on 11 May 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

OctoPrint before 1.6.0 allows XSS because API error messages include the values of input parameters.

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

## Which versions are affected by CVE-2021-32561?

3 open source packages ship an affected version, including octoprint and OctoPrint. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `octoprint` | PyPI | All versions | 1.6.0 |
| `octoprint` | PyPI | All versions | 1.6.0 |
| `OctoPrint` | PyPI | All versions | 1.6.0 |

Products: Octoprint Octoprint.

## How do I fix CVE-2021-32561?

Upgrade octoprint to 1.6.0 or later.

## Is CVE-2021-32561 being exploited?

There is no known exploitation of CVE-2021-32561 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2018-16710](https://insights.sbomify.com/CVE-2018-16710/): Information disclosure in n/a (critical 9.1)
- [CVE-2025-58180](https://insights.sbomify.com/CVE-2025-58180/): OctoPrint is Vulnerable to RCE Attacks via Unsanitized Filename in File Upload (high 7.5)
- [CVE-2022-1430](https://insights.sbomify.com/CVE-2022-1430/): Cross-site Scripting (XSS) - DOM in octoprint/octoprint (high 7.5)
- [CVE-2022-1432](https://insights.sbomify.com/CVE-2022-1432/): Cross-site Scripting (XSS) - Generic in octoprint/octoprint (high 7.5)
- [CVE-2024-32977](https://insights.sbomify.com/CVE-2024-32977/): OctoPrint Authentication Bypass via X-Forwarded-For Header when autologinLocal is enabled (high 7.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-32561 and fix it if it is affected.

What it is: CVE-2021-32561 is a medium-severity cross-site scripting vulnerability in n/a, published on 11 May 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-32561 in the wild and no public exploit code.

Affected packages and fixed versions:
- octoprint (PyPI): affected all versions; fixed in 1.6.0
- octoprint (PyPI): affected all versions; fixed in 1.6.0
- OctoPrint (PyPI): affected all versions; fixed in 1.6.0

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-2021-32561/ (Markdown: https://insights.sbomify.com/CVE-2021-32561/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32561
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32561
- OSV: https://osv.dev/vulnerability/CVE-2021-32561

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-32561/
Summaries are generated and may contain mistakes; the official description above is the record.