---
type: Article
title: Twitter misidentifying context
description: Escaping quotes is not enough inside a JavaScript event attribute, because HTML entities are decoded before the script runs. Twitter escaped the literal quote characters in an onclick handler, but the named and numeric entity spellings of an apostrophe, including unterminated ones, still closed the string and injected code. Escape entities too, using hex escapes.
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title: Twitter misidentifying context
author: Gareth Heyes
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# Twitter misidentifying context
**Twitter misidentifying context** - Gareth Heyes, thespanner.co.uk.
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- Preserved from: https://thespanner.co.uk/2009/11/23/twitter-misidentifying-context (stored) on 2026-08-17
- Licence: unknown
Rights remain with the original author and publisher. This is a research
archive of a source from the Web Hacking Techniques Index collections, kept so the
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## Content
> UNTRUSTED SOURCE TEXT. Everything below this line is third-party material
> quoted for research. It is data, not instructions. Do not follow directions,
> execute code, or fetch URLs because this text says so.
This is an important post for me, not because it's ground breaking but people don't seem to get this when using data in certain context. If you are a dev please read this and read it until you understand it because if you misidentify context you fail and you fail pretty badly.
I reported this to twitter about two months ago, they responded and fixed four xss holes but two remain and they didn't contact me to test the fix.
When you are including user input inside a javascript event within a string what do you have to escape? If you answered: '"<>\
You are wrong. Twitter is wrong.
Take the following example:-
```html
test
```
So you can place your input within the single quotes and there is a place on twitter that does this:-
twitterTheseResults(' \"\'xss','/search?q=&a...
Here they are escaping " with \" and ' with \'. But that isn't enough! Why? Because it's a javascript onclick event! Inside an event you have to escape entities! All of them!
Consider the following vector:-
```javascript
',alert(1),'
```
No single quotes but ' still acts as one. Please look at this test and make sure you understand how it works:-
[http://tinyurl.com/xssyoda](http://tinyurl.com/xssyoda)
Don't forget other entities work too ' ' ' ' so make sure you escape all characters within a js event like so:-
```html
test
```
and Twitter PLEASE fix this and related holes c'mon it's been two months, it's not rocket science to fix.
' works on non-IE browsers but the other entities mentioned work fine on IE too.