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             AUSCERT External Security Bulletin Redistribution

       CVE-2020-10663: Unsafe Object Creation Vulnerability in JSON
                             (Additional fix)
                               20 March 2020


        AusCERT Security Bulletin Summary

Product:           Ruby
Publisher:         Ruby
Operating System:  Windows
                   UNIX variants (UNIX, Linux, OSX)
Impact/Access:     Execute Arbitrary Code/Commands -- Remote/Unauthenticated
                   Denial of Service               -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2020-10663 CVE-2013-0269 

Reference:         ASB-2013.0028

Original Bulletin: 

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CVE-2020-10663: Unsafe Object Creation Vulnerability in JSON (Additional fix)

Posted by mame on 19 Mar 2020

There is an unsafe object creation vulnerability in the json gem bundled with
Ruby. This vulnerability has been assigned the CVE identifier CVE-2020-10663 .
We strongly recommend upgrading the json gem.


When parsing certain JSON documents, the json gem (including the one bundled
with Ruby) can be coerced into creating arbitrary objects in the target system.

This is the same issue as CVE-2013-0269 . The previous fix was incomplete,
which addressed JSON.parse(user_input) , but didn  t address some other styles
of JSON parsing including JSON(user_input) and JSON.parse(user_input, nil) .

See CVE-2013-0269 in detail. Note that the issue was exploitable to cause a
Denial of Service by creating many garbage-uncollectable Symbol objects, but
this kind of attack is no longer valid because Symbol objects are now
garbage-collectable. However, creating arbitrary objects may cause severe
security consequences depending upon the application code.

Please update the json gem to version 2.3.0 or later. You can use gem update
json to update it. If you are using bundler, please add gem "json", ">= 2.3.0"
to your Gemfile .

Affected versions

  o JSON gem 2.2.0 or prior


Thanks to Jeremy Evans for discovering this issue.


  o Originally published at 2020-03-19 13:00:00 (UTC)

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