'''Mass assignment''' is a [[vulnerability (computing)|computer vulnerability]] where an [[active record pattern]] in a [[web application]] is abused to modify data items that the user should not normally be allowed to access such as password, granted permissions, or administrator status.
Many [[web application framework]]s offer an [[active record pattern|active record]] featureand [[object-relational mapping]] features, where databaseexternal recorddata fieldsin can[[serialization]] be modifiedformats byis automatically generatedconverted webon APIinput methodsinto internal [[Object (computer science)|objects]] and, in turn, into database record fields. If the framework doesn'ts preventinterface for that automaticallyconversion andis thetoo permissive and application designer doesn't mark specific fields as immutable this way, it's possible to abuseoverwrite thefields APIthat callwere andnever modifyintented theseto hiddenbe fieldsmodified from outside (e.g. admin permissions flag).<ref>{{cite web | url=http://cwe.mitre.org/data/definitions/915.html | title=CWE-915: Improperly Controlled Modification of Dynamically-Determined Object Attributes | publisher=NIST | work=Common Weakness Enumeration | accessdate=February 27, 2013}}</ref>
These vulnerabilities were found in applications written in [[Ruby on Rails]],<ref>{{cite web | url=http://guides.rubyonrails.org/security.html#mass-assignment | title=Mass Assignment | work=Ruby On Rails Security Guide | accessdate=February 27, 2013}}</ref> [[ASP.NET MVC]],<ref>{{cite web | url=http://ironshay.com/post/Mass-Assignment-Vulnerability-in-ASPNET-MVC.aspx | title=Mass Assignment Vulnerability in ASP.NET MVC | publisher=IronsHay | accessdate=February 27, 2013}}</ref> [[Java (software platform)|Java]] [[Play framework]].<ref>{{cite web|url=http://alots.wordpress.com/2014/03/26/playframework-how-to-protect-against-mass-assignment/ |title=Playframework, how to protect against Mass Assignment |date=2014 |author=Alberto Souza}}</ref>
In 2012 mass assignment on Ruby on Rails wasallowed publishedbypassing thatof allowedmapping restrictions and resulted in [[proof of concept]] injection of unauthorized [[Secure Shell|SSH]] public keys into user accounts at [[GitHub]].<ref>{{cite web | url=http://www.zdnet.com/github-suspends-member-over-mass-assignment-hack-4010025556/ | title=GitHub suspends member over 'mass-assignment' hack | publisher=ZDnet | year=2012 | accessdate=February 27, 2013}}</ref><ref>{{cite web | url=http://weblog.rubyonrails.org/2013/2/11/SEC-ANN-Rails-3-2-12-3-1-11-and-2-3-17-have-been-released/ | title=[SEC][ANN] Rails 3.2.12, 3.1.11, and 2.3.17 have been released! | accessdate=2016 January 7}}</ref> Further vulnerabilities in Ruby on Rails allowed creation of internal objects through a specially crafted [[JSON]] structure.<ref>{{cite web | url=https://www.ruby-lang.org/en/news/2013/02/22/json-dos-cve-2013-0269/ | title=Denial of Service and Unsafe Object Creation Vulnerability in JSON (CVE-2013-0269) | accessdate=2016 January 7}}</ref>
