🛡️ CVE-2021-43818 — lxml

⚪ Unknown ✅ No Known Exploit CWE-74 OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

lxml's HTML Cleaner allows crafted and SVG embedded scripts to pass through

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.

Patches

The issue has been resolved in lxml 4.6.5.

Workarounds

None.

References

The issues are tracked under the report IDs GHSL-2021-1037 and GHSL-2021-1038.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. A user must be tricked into taking some action. Rated impact: confidentiality none, integrity none, availability none.

Affected software

CVE-2021-43818 is recorded against 1 package.

  • lxml (fixed in 4.6.5)

Timeline and source

Published on 13 December 2021 and last revised on 8 July 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from OSV.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Web)
github.com (Web)
github.com (Web)
www.oracle.com (Web)
www.oracle.com (Web)
www.debian.org (Web)
security.netapp.com (Web)
security.gentoo.org (Web)
lists.fedoraproject.org (Web)
lists.fedoraproject.org (Web)
lists.fedoraproject.org (Web)
lists.fedoraproject.org (Web)
lists.debian.org (Web)

CVE-2021-43818 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:H/SA:N
CWE CWE-74
Public Exploit ✅ No
Source OSV
Published 2021-12-13
Updated 2026-08-12
Modified 2026-07-08

Affected Packages

Software From version Fixed in
lxml 4.6.5

References

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