Seeding...

Invalid selector characters with a prefix of x - Shazzer

Invalid selector characters with a prefix of x

⚠ Browser differences

This vector uses an import inside a CSS string to test which characters cause an invalid CSS selector with a alpha prefix

Shazzer Master

Created Aug 6, 2026

Updated Aug 6, 2026

Unable to render tweet button

Detecting browser...

CategoryCSS Parsing

VisibilityPublic

TypeXSS

CharsetUTF-8

Template used:

<style>0x0D
x$[chr]{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

Code used after fuzz:

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

Sample payloads

Hide older browsersShowing 2 of 3

⚠Chrome 151.0.7922.75 desktop Linux

Updated7 Aug 2026

Found 51 results

Show differences only?

Filter out alphanumeric

Sort ascending

⚠Firefox 153.0 desktop Linux

Updated7 Aug 2026

Found 1 result

Show differences only?

Filter out alphanumeric

Sort ascending

<style>0x0D
x0x01{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x02{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x03{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x04{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x05{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x06{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x07{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x08{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x0B{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x0E{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x0F{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x10{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x11{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x12{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x13{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x14{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x15{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x16{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x17{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>

<style>0x0D
x0x18{position:"⟦0D⟧
}@import'data:text/css,%23x{color:red}';⟦0D⟧
</style>0x0D
<div id="x">test</div>