lxml <6.1.1: Missing xlink:href in link_attrs Enables URL Bypass (SVG/MathML)
CVE-2026-49825 Published on August 20, 2026

lxml: javascript: URL bypass in Cleaner via xlink:href
lxml is a library for processing XML and HTML in the Python language. Prior to 6.1.1, link attributes in ``lxml.html.defs.link_attrs`` were missing ``xlink:href``, which can be used for URL bypass attacks in embedded SVG/MathML/etc. content. This vulnerability was fixed in lxml 6.1.1 and lxml_html_clean 0.4.5.

Vendor Advisory NVD

Vulnerability Analysis

CVE-2026-49825 can be exploited with network access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity, and no impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
REQUIRED
Scope:
CHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
LOW
Availability Impact:
NONE

Weakness Types

What is a XSS Vulnerability?

The software does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

CVE-2026-49825 has been classified to as a XSS vulnerability or weakness.

What is a Denylist / Deny List Vulnerability?

The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are not allowed by policy or otherwise require other action to neutralize before additional processing takes place, but the list is incomplete, leading to resultant weaknesses. Developers often try to protect their products against malicious input by performing tests against inputs that are known to be bad, such as special characters that can invoke new commands. However, such lists often only account for the most well-known bad inputs. Attackers may be able to find other malicious inputs that were not expected by the developer, allowing them to bypass the intended protection mechanism.

CVE-2026-49825 has been classified to as a Denylist / Deny List vulnerability or weakness.


Products Associated with CVE-2026-49825

Want to know whenever a new CVE is published for Lxml? stack.watch will email you.

Lxml
 

Affected Versions

lxml: fedora-python lxml_html_clean: