Bug 1412245 (CVE-2016-7478)

Summary: CVE-2016-7478 php: Unserialize Exception object can lead to infinite loop
Product: [Other] Security Response Reporter: Adam Mariš <amaris>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED WONTFIX QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: abhgupta, hhorak, jorton, kseifried, rcollet, sardella, tiwillia
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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Last Closed: 2017-01-11 15:37:22 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Adam Mariš 2017-01-11 15:35:34 UTC 
It was found that specially crafted input to unserialize, an exception object which refers to itself as the previous exception, may cause exception::__toString never to terminate, causing infinite loop.

Upstream bug:

https://bugs.php.net/bug.php?id=73093

External Reference:

https://blog.checkpoint.com/wp-content/uploads/2016/12/PHP_Technical_Report.pdf
Comment 1 Adam Mariš 2017-01-11 15:37:22 UTC 
This issue happens when untrusted input is unserialized. Doing so is documented as being unsafe:

  http://php.net/manual/en/function.unserialize.php

  Do not pass untrusted user input to unserialize(). Unserialization can
  result in code being loaded and executed due to object instantiation and
  autoloading, and a malicious user may be able to exploit this. Use a safe,
  standard data interchange format such as JSON (via json_decode() and
  json_encode()) if you need to pass serialized data to the user.