An XSS vulnerability was discovered in python-lxml's clean module versions before 4.6.3. When disabling the safe_attrs_only and forms arguments, the Cleaner class does not remove the formaction attribute allowing for JS to bypass the sanitizer. A remote attacker could exploit this flaw to run arbitrary JS code on users who interact with incorrectly sanitized HTML. This issue is patched in lxml 4.6.3.
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Tracking
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Advisories
| Source | ID | Title |
|---|---|---|
Debian DLA |
DLA-2606-1 | lxml security update |
Debian DSA |
DSA-4880-1 | lxml security update |
EUVD |
EUVD-2021-0116 | An XSS vulnerability was discovered in python-lxml's clean module versions before 4.6.3. When disabling the safe_attrs_only and forms arguments, the Cleaner class does not remove the formaction attribute allowing for JS to bypass the sanitizer. A remote attacker could exploit this flaw to run arbitrary JS code on users who interact with incorrectly sanitized HTML. This issue is patched in lxml 4.6.3. |
Github GHSA |
GHSA-jq4v-f5q6-mjqq | lxml vulnerable to Cross-Site Scripting |
Ubuntu USN |
USN-4896-1 | lxml vulnerability |
Ubuntu USN |
USN-4896-2 | lxml vulnerability |
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Wed, 17 Dec 2025 22:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
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Status: PUBLISHED
Assigner: mitre
Published:
Updated: 2025-12-17T21:31:43.446Z
Reserved: 2021-03-21T00:00:00.000Z
Link: CVE-2021-28957
Updated: 2024-08-03T21:55:12.376Z
Status : Modified
Published: 2021-03-21T05:15:13.367
Modified: 2025-12-17T22:15:56.740
Link: CVE-2021-28957
OpenCVE Enrichment
No data.
Weaknesses
Debian DLA
Debian DSA
EUVD
Github GHSA
Ubuntu USN