Issue #11855 has been reported by Kazuhiro NISHIYAMA.

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Bug #11855: CGI.escapeHTML and taint/frozen
https://bugs.ruby-lang.org/issues/11855

* Author: Kazuhiro NISHIYAMA
* Status: Open
* Priority: Normal
* Assignee: 
* ruby -v: ruby 2.3.0dev (2015-12-21 trunk 53230) [x86_64-darwin14]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
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taint フラグや frozen の扱いが変わってしまっているようです。

~~~
% ruby -v -r cgi -e 'p CGI.escapeHTML("".taint).tainted?'
ruby 2.3.0dev (2015-12-21 trunk 53230) [x86_64-darwin14]
true
% ruby -v -r cgi -e 'p CGI.escapeHTML("&".taint).tainted?'
ruby 2.3.0dev (2015-12-21 trunk 53230) [x86_64-darwin14]
false
% ruby -v -r cgi -e 'p CGI.escapeHTML("".freeze).frozen?'
ruby 2.3.0dev (2015-12-21 trunk 53230) [x86_64-darwin14]
true
% ruby -v -r cgi -e 'p CGI.escapeHTML("&".freeze).frozen?'
ruby 2.3.0dev (2015-12-21 trunk 53230) [x86_64-darwin14]
false
~~~

~~~
% ruby -v -r cgi -e 'p CGI.escapeHTML("".taint).tainted?'
ruby 2.2.4p230 (2015-12-16 revision 53155) [x86_64-darwin14]
true
% ruby -v -r cgi -e 'p CGI.escapeHTML("&".taint).tainted?'
ruby 2.2.4p230 (2015-12-16 revision 53155) [x86_64-darwin14]
true
% ruby -v -r cgi -e 'p CGI.escapeHTML("".freeze).frozen?'
ruby 2.2.4p230 (2015-12-16 revision 53155) [x86_64-darwin14]
false
% ruby -v -r cgi -e 'p CGI.escapeHTML("&".freeze).frozen?'
ruby 2.2.4p230 (2015-12-16 revision 53155) [x86_64-darwin14]
false
~~~




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