DEBIAN-CVE-2021-28957

Advisory lineage Upstream: 1 Downstream: 2
Upstream
CVE-2021-28957
Published: 21 Mar 2021, 05:15
Last modified:28 Apr 2026, 20:22

Vulnerability Summary

Overall Risk (default)
low
24/100
CVSS Score
6.1 MEDIUM
3.1 (osv_debian)
EPSS Score
No data
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

21 Mar 2021, 05:15
Published
Vulnerability first disclosed
28 Apr 2026, 20:22
Last Modified
Vulnerability information updated

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

  • v3.1•MEDIUM•Score: 6.1CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected Systems

  • debian•lxml

    < 4.6.3-1 | < 4.6.3-1 | < 4.6.3-1 | < 4.6.3-1

References (1)