lxml's HTML Cleaner allows crafted and SVG embedded scripts to pass through
Published Dec 13, 2021 · Updated Nov 3, 2026
Original summary
Normalized public record · Updated Nov 3, 2026
lxml's HTML Cleaner allows crafted and SVG embedded scripts to pass through
Publisher and source text is retained separately from QFinch interpretation.
QFinch assessment
The HTML Cleaner in lxml.html lets certain crafted script content pass through, as well as script content in SVG files embedded using data URIs.
Potential impact
The HTML Cleaner in lxml.html lets certain crafted script content pass through, as well as script content in SVG files embedded using data URIs. Users that employ the HTML cleaner in a security relevant context should upgrade to lxml 4.6.5.
Evidence: public source recordsAffected products
| Affected package, product or range | Fix status |
|---|---|
| Consult the referenced vendor advisory for affected versions. | Consult source advisory |
Matching a version is only one part of assessing exposure. QFinch has not assessed your environment on this public page.
Remediation
Apply the vendor-supported fixed release or mitigation, then verify the affected component is no longer reachable.
- Confirm the affected product and reachable code path exist in your environment.
- Apply the vendor-supported patch or mitigation from the primary advisory.
- Rescan the exact deployed revision and retain verification evidence.
Evidence coverage
- SSVC priority
- MEDIUM
- Confidence
- Not available
- Aliases
- None reported
Scores appear only when corresponding evidence exists. Missing data is never interpreted as zero risk.
Sources and record history
- Security advisory ↗
- Patch commit ↗
- Patch commit ↗
- Patch commit ↗
- FEDORA-2021-6e8fb79f90 ↗
- FEDORA-2021-9f9e7c5c4f ↗
- [debian-lts-announce] 20211230 [SECURITY] [DLA 2871-1] lxml security update ↗
- DSA-5043 ↗
- FEDORA-2022-96c79bf003 ↗
- FEDORA-2022-7129fbaeed ↗
- www.oracle.com ↗
- security.netapp.com ↗
Record history
Published Dec 13, 2021 · Last refreshed Nov 3, 2026