How severe is CVE-2021-41146?

CVE-2021-41146 has a CVSS score of 8.8/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-41146?

CVE-2021-41146 affects the following packages: qutebrowser (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2021-41146?

Update qutebrowser to 2.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-41146 is resolved across your whole dependency graph.

How do I detect CVE-2021-41146 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for qutebrowser, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-41146 if there is no patch (or I can't update yet)?

Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Is CVE-2021-41146 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-41146 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-41146?

CVE-2021-41146 has an EPSS (Exploit Prediction Scoring System) score of 1.5%, placing it in the 73th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-41146?

CVE-2021-41146 is classified as CWE-77 (CWE-77), CWE-88 (CWE-88), CWE-641 (CWE-641). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-41146 published, and has it been updated?

CVE-2021-41146 was published on October 21, 2021 and was last updated on July 9, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

HIGH severity

CVE-2021-41146 — qutebrowser

HIGHFix: qutebrowser/qutebrowser@8f46ba3

CVE-2021-41146 is a high-severity (CVSS 8.8) CWE-77 vulnerability in qutebrowser. A fix is available for qutebrowser — see the affected versions and patch details below.

Arbitrary command execution on Windows via qutebrowserurl: URL handler

Also known asGHSA-vw27-fwjf-5qxmPYSEC-2021-382

Published

Oct 21, 2021

Updated

Jul 9, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs73th percentile — riskier than 73% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-41146 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 384,534 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

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

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`qutebrowser`	≥ 1.7.0&&< 2.4.0	2.4.0`pip install --upgrade 'qutebrowser==2.4.0'`

Affected Products

1 product · 2 configurations

Application

qutebrowserqutebrowser

≥ 2.0.0 && ≤ 1.7.0

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for qutebrowser, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update qutebrowser to 2.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-41146 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

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.