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Case File

CVE-2021-28957

MEDIUM · CVSS 6.1 EPSS 4.00% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2021-03-21 · Last synced 2026-08-04

CyberRota Analysis

This is a medium severity vulnerability with a CVSS score of 6.1. Public exploit code or proof-of-concept references have been detected in its references. It may be remotely exploitable.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Detected Signals
exploit

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2021-28957
Severity
MEDIUM
CVSS
6.1
EPSS
4.00%

Original NVD 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.

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