# CVE-2021-41146: Arbitrary command execution on Windows in qutebrowser

> Attackers can execute arbitrary code on Windows by tricking users into opening a crafted URL if qutebrowser is registered as the default handler.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **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:** 21 Oct 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-vw27-fwjf-5qxm, PYSEC-2021-382

## What is CVE-2021-41146?

CVE-2021-41146 is a high-severity command injection vulnerability in qutebrowser, published on 21 Oct 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

qutebrowser is an open source keyboard-focused browser with a minimal GUI. Starting with qutebrowser v1.7.0, the Windows installer for qutebrowser registers a `qutebrowserurl:` URL handler. With certain applications, opening a specially crafted `qutebrowserurl:...` URL can lead to execution of qutebrowser commands, which in turn allows arbitrary code execution via commands such as `:spawn` or `:debug-pyeval`. Only Windows installs where qutebrowser is registered as URL handler are affected. The issue has been fixed in qutebrowser v2.4.0. The fix also adds additional hardening for potential similar issues on Linux (by adding the new --untrusted-args flag to the .desktop file), though no such vulnerabilities are known.

Weakness: CWE-88 (Improper Neutralization of Argument Delimiters in a Command), CWE-77 (Improper Neutralization of Special Elements used in a Command), CWE-641 (Improper Restriction of Names for Files and Other Resources)

## Which versions are affected by CVE-2021-41146?

3 open source packages ship an affected version, including qutebrowser. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `qutebrowser` | PyPI | All versions | 1.8.0, 2.4.0 |
| `qutebrowser` | PyPI | From 1.7.0 | 2.4.0 |
| `qutebrowser` | PyPI | From 1.7.0 | 2.4.0 |

Products: Qutebrowser Qutebrowser.

## How do I fix CVE-2021-41146?

Upgrade qutebrowser to a fixed version for your release line: 1.8.0 or 2.4.0.

## Is CVE-2021-41146 being exploited?

There is no known exploitation of CVE-2021-41146 in the wild and no public exploit code.

## Other vulnerabilities in qutebrowser

- [CVE-2018-10895](https://insights.sbomify.com/CVE-2018-10895/): Qutebrowser CSRF Vulnerability (critical 9.3)
- [CVE-2018-1000559](https://insights.sbomify.com/CVE-2018-1000559/): Qutebrowser XSS Vulnerability (medium 6.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-41146 and fix it if it is affected.

What it is: CVE-2021-41146 is a high-severity command injection vulnerability in qutebrowser, published on 21 Oct 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-2021-41146 in the wild and no public exploit code.

Affected packages and fixed versions:
- qutebrowser (PyPI): affected all versions; fixed in 1.8.0, 2.4.0
- qutebrowser (PyPI): affected from 1.7.0; fixed in 2.4.0
- qutebrowser (PyPI): affected from 1.7.0; fixed in 2.4.0

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-2021-41146/ (Markdown: https://insights.sbomify.com/CVE-2021-41146/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-41146
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-41146
- OSV: https://osv.dev/vulnerability/CVE-2021-41146

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-41146/
Summaries are generated and may contain mistakes; the official description above is the record.