CVE-2021-28957
Medium
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.
SeverityMedium
CVSS6.1
Exploit probability—
Product
Lxml
PublishedMar 21, 2021
First seenMar 21, 2021
Weakness typeCWE-79Cross-site scripting (XSS)
How to fix
Update
- lxml lxml4.6.3 or later
- lxml4.6.3 or later
Vendor advisories
- debian.org/security/2021/dsa-4880
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ/
- security.gentoo.org/glsa/202208-06
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| lxml lxml | v < 4.6.3 | 4.6.3 |
| debian debian_linux | 9.0, 10.0 | — |
| fedoraproject fedora | 33, 34 | — |
| netapp snapcenter | No range specified | — |
| oracle zfs_storage_appliance_kit | 8.8 | — |
| lxmlPyPI | v < 4.6.3 | 4.6.3 |
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