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🐍 PyPI

GHSA-vw27-fwjf-5qxm

HIGH

Arbitrary command execution on Windows via qutebrowserurl: URL handler

Also known asCVE-2021-41146PYSEC-2021-382
Published
Oct 22, 2021
Updated
Mar 13, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed

EPSS Exploitation Probability

via FIRST.org ↗
1.4%probability of exploitation in next 30 days
Lower Risk70th percentile+0.70%
0.24%0.81%1.38%1.95%0.8%1.4%Dec 25Apr 26Jun 26

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected
🐍qutebrowser

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

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 [email protected] 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 [email protected].

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIqutebrowser≥ 1.7.0&&< 2.4.02.4.0

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for qutebrowser. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update qutebrowser to 2.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vw27-fwjf-5qxm is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether GHSA-vw27-fwjf-5qxm is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-vw27-fwjf-5qxm. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### 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.
O3 Security · Impact-Aware SCA

Is GHSA-vw27-fwjf-5qxm in your dependencies?

O3 detects GHSA-vw27-fwjf-5qxm across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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