Preliminary research

CSS property and URL allowlists can be bypassed via CSS nesting in stylesheets

AI-collected research leads through 3 November 2026, including a November–October–September missed-article review and a targeted multilingual search alongside earlier community-source sweeps. Unranked, incomplete, not community-vetted, and subject to change.

A sanitizer treats brace-bearing text as a permitted declaration value or selector while a nesting-capable browser parses new rules and declarations. Context determines whether property and URL restrictions survive.

Record

Published by

Sanitize project

Date

21 October 2026

Format

Advisory

In the archive

• Collected in the 2026 preliminary research sweep

Tags

• css
• css-injection
• parser-differential
• owasp-a03-2021

This page is the archive's own catalogue record. The research is the work of Sanitize project, first published at the original source. Preserved copies are kept so the citation survives its host.