Steps to reproduce:

1. Upload this PDF file to Confluence page: Panasonic_NiMH_HHR70AAAJ.pdf
2. Go to Insert > Other Macros > PDF
3. Try to preview this PDF.
4. Confluence will crash.

Error in atlassian-confluence.log:

2013-09-10 16:33:01,427 WARN [http-8523-3] [com.benryan.conversion.PPTSlideServlet] doGet Conversion task timed out for attachment : Panasonic_NiMH_HHR70AAAJ.pdf with page number 0, waited : 300, now executing in background.
 -- url: /confluence/plugins/servlet/pptslide | userName: admin
2013-09-10 16:33:01,750 WARN [http-8523-3] [com.benryan.conversion.PPTSlideServlet] doGet Conversion task timed out for attachment : Panasonic_NiMH_HHR70AAAJ.pdf with page number 0, waited : 300, now executing in background.
 -- url: /confluence/plugins/servlet/pptslide | userName: admin
2013-09-10 16:33:02,069 WARN [http-8523-3] [com.benryan.conversion.PPTSlideServlet] doGet Conversion task timed out for attachment : Panasonic_NiMH_HHR70AAAJ.pdf with page number 0, waited : 300, now executing in background.
 -- url: /confluence/plugins/servlet/pptslide | userName: admin
2013-09-10 16:33:02,384 WARN [http-8523-3] [com.benryan.conversion.PPTSlideServlet] doGet Conversion task timed out for attachment : Panasonic_NiMH_HHR70AAAJ.pdf with page number 0, waited : 300, now executing in background.
 -- url: /confluence/plugins/servlet/pptslide | userName: admin
2013-09-10 16:33:37,774 WARN [http-8523-3] [com.benryan.conversion.PPTSlideServlet] doGet Conversion task timed out for attachment : Panasonic_NiMH_HHR70AAAJ.pdf with page number 0, waited : 300, now executing in background.
 -- url: /confluence/plugins/servlet/pptslide | userName: admin.

Tomcat window freezed:

Java process hanged:

Workaround:

Insert the PDF file into Confluence page using HTML macro in combination with iframe:

1. Enable HTML macro module ((html-xhtml) from Manage Add-Ons > System Plugins > Confluence HTML Macros
2. Go to a Confluence page > Insert > Other Macros > HTML
3. Inside the HTML tag include the following iframe:

   <iframe src="http://confluence.atlassian.com/confluence/download/attachments/1114129/Panasonic_NiMH_HHR70AAAJ.pdf?api=v2" width="100%" style="height:50em" />
   

4. Save page
5. Result: The PDF is rendered fine in the page and Confluence is not crashing

Note: You may replace the attachment link accordingly

In 5.2.3, you'll need to check/tick the 'Insecure: Display all attachments inline' setting in Confluence Admin > Security Configurations > Attachment Download Security Policy so that Confluence will not try to download the PDF file into your local machine and just render it in the page.

While this may be a legit workaround it has two major problems:

1. PDF only gets rendered if you have an Adobe Reader Plugin or you use Firefox which uses pdf.js
2. Confluence can crash any time since a user can upload a PDF and try to render it using viewxls.

Possible Workaround one of customers reported that upgrading java to version 7u55 stabilised the instance from the occurrence of crashes.