Description
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.
CVSS Metrics
- Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- Attack Vector
- network
- Complexity
- low
- Privileges
- none
- User Action
- required
- Scope
- changed
- Confidentiality
- low
- Integrity
- low
- Availability
- none
- Weaknesses
- CWE-79CWE-79
Metadata
- Primary Vendor
- LXML
- Published
- 3/21/2021
- Last Modified
- 12/17/2025
- Source
- NIST NVD
- Note: Verify all details with official vendor sources before applying patches.
Affected Products
lxml : lxmldebian : debian_linuxdebian : debian_linuxfedoraproject : fedorafedoraproject : fedoranetapp : snapcenteroracle : zfs_storage_appliance_kit
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