Pwning...

Characters that break CSS dangling strings

This vector shows which characters create a new selector if there is a dangling CSS string

Shazzer Master

Created byhackvertor

Created Aug 6, 2026

Updated Sep 5, 2026

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CategoryCSS Parsing

VisibilityPublic

TypeXSS

CharsetUTF-8

Template used:

<style>
.x{
   font-family:"foo, bar, baz$[chr]}.x{color:red;
}
</style>
<div id=x class="x">test</div>

Code used after fuzz:

window.getComputedStyle(x).color === 'rgb(255, 0, 0)' && log($[i])

Sample payloads

<style>
.x{
   font-family:"foo, bar, baz
}.x{color:red;
}
</style>
<div id=x class="x">test</div>

<style>
.x{
   font-family:"foo, bar, baz⟦0C⟧}.x{color:red;
}
</style>
<div id=x class="x">test</div>

<style>
.x{
   font-family:"foo, bar, baz
}.x{color:red;
}
</style>
<div id=x class="x">test</div>

<style>
.x{
   font-family:"foo, bar, baz"}.x{color:red;
}
</style>
<div id=x class="x">test</div>