Relative-link hijacking via preserved base tags
Published Mar 5, 2026 · Updated Mar 5, 2026
HTML injection in fedora-python lxml_html_clean before 0.4.4 allows remote attackers to hijack relative URLs through crafted HTML. The default Cleaner page-structure pass removes head but omits base from its kill set, so browsers retain an attacker-supplied base URL. Exploitation requires an application to sanitize attacker-controlled HTML and render the result; browsers then resolve relative links, forms, assets, and scripts to an attacker-controlled domain.
Summary
What happened
HTML injection in fedora-python lxml_html_clean before 0.4.4 allows remote attackers to hijack relative URLs through crafted HTML. The default Cleaner page-structure pass removes head but omits base from its kill set, so browsers retain an attacker-supplied base URL. Exploitation requires an application to sanitize attacker-controlled HTML and render the result; browsers then resolve relative links, forms, assets, and scripts to an attacker-controlled domain.
The record
- CVE
- CVE-2026-28350
- Published
- Mar 5, 2026
- Updated
- Mar 5, 2026
- Vendor
- fedora-python
- Product
- lxml_html_clean
- Classifications
- CWE-116, T1189
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 5, 2026CVE publishedPublication date reported by the CVE source.
- Mar 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 0.4.4
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- Upstream base-tag injection proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo