Arbitrary command execution on Windows via qutebrowserurl: URL handler
Impact
Starting with qutebrowser v1.7.0, the Windows installer for qutebrowser registers it as a handler for certain URL schemes. With some applications such as Outlook Desktop, opening a specially crafted URL can lead to argument injection, allowing 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. It does not have to be set as default browser for the exploit to work.
Patches
The issue has been fixed in qutebrowser v2.4.0 in commit 8f46ba3f6dc7b18375f7aa63c48a1fe461190430.
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.
Backported patches for older versions are available, but no further releases are planned:
- v1.7.x: d1ceaab
- v1.8.x: ca7155d
- v1.9.x: 157d871
- v1.10.x: 94a6125
- v1.11.x: 10acfbb
- v1.12.x: 363a18f
- v1.13.x: 410f262
- v1.14.x: e4f4d93
- v2.0.x: 15a1654
- v2.1.x: 509ddf2
- v2.2.x: 03dcba5
- v2.3.x: 00a694c
(commits are referring to qutebrowser/qutebrowser on GitHub)
Workarounds
Remove qutebrowser from the default browser settings entirely, so that it does not handle any kind of URLs. Make sure to remove all handlers, including an (accidental) qutebrowserURL handler, e.g. using NirSoft URLProtocolView.
Timeline
2021-10-15: Issue reported via security@qutebrowser.org by Ping Fan (Zetta) Ke of Valkyrie-X Security Research Group (VXRL) 2021-10-15: Issue confirmed by @The-Compiler (lead developer), author of installer (@bitraid) contacted for help/review 2021-10-15: CVE assigned by GitHub 2021-10-15 to 2021-10-17: Fix developed 2021-10-17: Additional core developer (@toofar) contacted for help/review 2021-10-21: v2.4.0 released containing the fix 2021-10-21: Advisory and fix published
References
See the commit message for additional information and references to various similar issues in other projects.
Acknowledgements
Thanks to Ping Fan (Zetta) Ke of Valkyrie-X Security Research Group (VXRL/@vxresearch) for finding and responsibly disclosing this issue.
Contact
If you have any questions or comments about this advisory, please email security@qutebrowser.org.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | qutebrowser | >= 1.7.0, < 2.4.0 | 2.4.0 |
References
- https://github.com/qutebrowser/qutebrowser/security/advisories/GHSA-vw27-fwjf-5qxm
- https://github.com/qutebrowser/qutebrowser/commit/8f46ba3f6dc7b18375f7aa63c48a1fe461190430
- https://nvd.nist.gov/vuln/detail/CVE-2021-41146
- https://github.com/pypa/advisory-database/tree/main/vulns/qutebrowser/PYSEC-2021-382.yaml
- https://github.com/qutebrowser/qutebrowser
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H- Weakness (CWE)
CWE-641, CWE-77, CWE-88- Platform
- Python (PyPI)
- Package
qutebrowser- Disclosed
- 21.10.2021
- Updated
- 11.10.2026 13:19
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2021-382 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-vw27-fwjf-5qxm - CC BY 4.0
Vulnerability history: qutebrowser
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 4
- First → latest
- 06.2018 10.2021
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 2
- Medium 1
- Low 1
Disclosures per year
- 2018: 2
- 2019: 0
- 2020: 1
- 2021: 1
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 0
-
Arbitrary command execution on Windows via qutebrowserurl: URL handler this entry
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.