CVE-2026-28350
March 05, 2026
Summary The "<base>" tag passes through the default "Cleaner" configuration. While "page_structure=True" removes "html", "head", and "title" tags, there is no specific handling for "<base>", allowing an attacker to inject it and hijack relative links on the page. Details The "<base>" tag is not currently in the "page_structure" kill set. Even though the specification says "<base>" must be inside "<head>", browsers accept "<base>" tags outside of the head. If an attacker injects a "<base>" tag, it changes the base URL for all relative URLs on the page (links, images, scripts) to a domain controlled by the attacker.
Affected Packages
lxml-html-clean (CONDA):
Affected version(s) >=0.1.1 <0.4.4Fix Suggestion:
Update to version 0.4.4https://github.com/fedora-python/lxml_html_clean.git (GITHUB):
Affected version(s) >=0.4.0 <0.4.4Fix Suggestion:
Update to version 0.4.4lxml-html-clean (PYTHON):
Affected version(s) >=0.1.0 <0.4.4Fix Suggestion:
Update to version 0.4.4Additional Notes
The description of this vulnerability differs from MITRE.
Related Resources (4)
Do you need more information?
Contact UsCVSS v4
Base Score:
5.3
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
PASSIVE
Vulnerable System Confidentiality
LOW
Vulnerable System Integrity
LOW
Vulnerable System Availability
NONE
Subsequent System Confidentiality
LOW
Subsequent System Integrity
LOW
Subsequent System Availability
NONE
CVSS v3
Base Score:
6.1
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Weakness Type (CWE)
Improper Encoding or Escaping of Output
EPSS
Base Score:
0.01
