OWASP Top 10 Privacy Risks Project

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The project in a nutshell

The OWASP Top 10 Privacy Risks Project provides a top 10 list for privacy risks in web applications. The Project involves Privacy and security experts from all over the world who discuss and rate current privacy issues. The result is a list covering technological and organizational aspects that focus on real-life risks, not just legal issues. It uses the OECD Privacy Guidelines as a framework, with the aim of helping developers and web application providers to better understand and improve privacy. The list can also be used to assess privacy risks associated with specific web applications.

Top 10 Privacy Risks 2014 (Alpha Release)

P1    Web Application Vulnerabilities
P2    Operator-sided Data Leakage
P3    Insufficient Data Breach Response
P4    Insufficient Deletion of personal data
P5    Non-transparent Policies, Terms and Conditions
P6    Collection of data not required for the primary purpose
P7    Sharing of data with third party
P8    Outdated personal data
P9    Missing or Insufficient Session Expiration
P10  Insecure Data Transfer

Further information is provided in the Top 10 Privacy Risks tab.

Contact us

Project Leader

Florian Stahl

Quick Download


OWASP Top 10 Privacy Risks Project is free to use. It is licensed under the Creative Commons CC-BY-SA v3.0 License.

Download Infographic version

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News & Events

  • [20 Feb 2014] Project Start
  • [26 Aug 2014] Survey results published
  • [21 Sep 2014] Top 10 Privacy Risks v1.0 published
  • [5 Mar 2015] Presentation at IAPP Global Privacy Summit, Washington DC
  • [21-22 May 2015] Presentation at AppSecEU

External Links

OECD Privacy Guidelines Internet Privacy Engineering Network - IPEN
Video from IPEN workshop at Berlin state parliament
Video from panel discussion at CPDP 2015 in Brussels
IAPP blogs about the project


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Project Type Files DOC.jpg

Top 10 Privacy Risks 2014 (Alpha Release)

Alpha Release Version 1.0 of the OWASP Top 10 Privacy Risks list. For background information check the Discussions and Documentation section.

No. Title Frequency Impact     Description
P1 Web Application Vulnerabilities High Very high Vulnerability is a key problem in any system that guards or operates on sensitive user data. Failure to suitably design and implement an application, detect a problem or promptly apply a fix (patch) is likely to result in a privacy breach. This risk also encompasses the OWASP Top 10 List of web application vulnerabilities and the risks resulting from them.
P2 Operator-sided Data Leakage High Very high Failure to prevent the leakage of any information containing or related to user data, or the data itself, to any unauthorized party resulting in loss of data confidentiality. Introduced either due to intentional malicious breach or unintentional mistake e.g. caused by insufficient access management controls, insecure storage, duplication of data or a lack of awareness.
P3 Insufficient Data Breach Response High Very high Not informing the affected persons (data subjects) about a possible breach or data leak, resulting either from intentional or unintentional events; failure to remedy the situation by fixing the cause; not attempting to limit the leaks.
P4 Insufficient Deletion of Personal Data Very high High Failure to effectively and/or timely delete personal data after termination of the specified purpose or upon request.
P5 Non-transparent Policies, Terms and Conditions Very high High Not providing sufficient information to describing how data is processed, such as its collection, storage, and processing. Failure to make this information easily-accessible and understandable for non-lawyers.
P6 Collection of data not required for the primary purpose Very high High Collecting descriptive, demographic or any other user-related data that are not needed for the purposes of the system. Applies also to data for which the user did not provide consent.
P7 Sharing of Data with Third Party High High Providing user data to any third-party, without obtaining the user’s consent. Sharing results either due to transfer or exchanging for a monetary compensation or otherwise due to inappropriate use of third-party resources included in the web site like widgets (e.g. maps, social networks buttons), analytics or web bugs (e.g. beacons).
P8 Outdated personal data High Very high The use of outdated, incorrect or bogus user data. Failure to update or correct the data.
P9 Missing or insufficient Session Expiration Medium Very high Failure to effectively enforce session termination. May result in collection of additional user-data without the user’s consent or awareness.
P10 Insecure Data Transfer Medium Very high Failure to provide data transfers over encrypted and secured channels, excluding the possibility of data leakage. Failure of enforcing mechanisms limiting the leak surface, e.g. allowing to infer any user data out of the mechanics of Web application operation.

Note: The values between 0 to 3 used for frequency and impact rating were replaced by a textual description: 0-1: Low, 1-1.5: Medium, 1.5-2: High, > 2: Very high


  • 20 February 2014: Project start
  • ...
  • 21 September 2014: Publication of v1.0 of the Top 10 Privacy Risks
  • 26 September 2014: Initial results presentation at the IPEN Workshop in Berlin State Parliament
  • 9 December 2014: Results presentation at German OWASP Day in Hamburg
  • 10 December 2015: Start collection of countermeasures
  • 2015: Define a core team for improvement and further development
  • 2015: Further promotion of the Top 10 Privacy Risks Project
  • 2015: Improvements, development of countermeasures and version 2


Some ways you can help:

  • Discuss with us in the Discussions and documentation section
  • Tell your colleagues and friends about the project
  • Provide feedback (feel free to contact us)
  • Apply the results in practice to improve web application privacy

Sign up to our mailing list to stay informed.

OWASP Top 10 Privacy Risks Survey

A survey was performed to determine the frequency of occurrence of privacy violations in web applications.

63 people participated in total. The survey was online for 3 weeks from 4 to 25 August 2014.

Here is a summary of the results or you can download the full report.

Part 1:

Q1 Do or did you work as a:

Software Developer 26.98%

Software Designer 12.70%

Legal Practitioner 4.76%

Software Project Manager 11.11%

Data Privacy Expert 33.33%

Security Expert 66.67%

Public Servant 12.70%

Other 11.11%

Q2 In total, how many years of professional experience do you have related to privacy?

Average: 6.2 years

Q3 In total, how many years of professional experience do you have related to web applications?

Average: 8.1 years

Part 2:

The following ratings are between 1 and 4.

The possible choices for answers where:

[1] Up to one out of four web applications. (0-25%)

[2] Up to ev ery second web application. (26-50%)

[3] Up to three out of four web applications. (51-75%)

[4] More than three out of four web applications. (76-100%)

[excluded] N/A

01. Collection of data not required for main purpose

Average Rating: 3.1

02. Collection of Incorrect Data

Average Rating: 2.0

03. Collection without consent

Average Rating: 3.0

04. Problems with getting Consent

Average Rating: 2.6

05. Outdated Personal Data

Average Rating: 2.6

06. Inability of users to modify stored data

Average Rating: 2.3

07. Insufficient deletion of personal data

Average Rating: 3.3

08. Unrelated use

Average Rating: 2.7

09. Data Aggregation and Profiling

Average Rating: 2.4

10. Sharing of data with third party

Average Rating: 2.8

11. Operator-sided Data Leakage

Average Rating: 2.7

12. Insecure data transfer

Average Rating: 2.3

13. Web Application Vulnerabilities

Average Rating: 2.9

14. Insufficient Data Breach Response

Average Rating: 2.6

15. Form field design issues

Average Rating: 2.2

16. Missing or Insufficient Session Expiration

Average Rating: 2.4

17. Misleading Content

Average Rating: 2.3

18. Non-transparent Policies, Terms and Conditions

Average Rating: 3.2

19. Inappropriate Policies, Terms and Conditions

Average Rating: 2.7

20. Transfer or processing through third party

Average Rating: 2.6

Frequently Asked Questions

Why is this project only about web applications and not about any kind of software?

Web applications can easily collect data from users without their permission or without adequately informing them how their data is used. Cookies, and other trackers, enable the monitoring of user's behaviour, and this information may be used for a variety of commercial purposes, including targeted advertising, profiling, and the sale of aggregated data. This is why the subject is so important, especially for web applications.

What is the difference between this project and the OWASP Top 10?

There are two main differences. First, the OWASP top 10 describes technical risks, that are not primarily affecting privacy. Second, the OWASP Top 10 doesn't address software such as cookies or trackers, or organisational issues like privacy notices, profiling, or the sharing of data with third parties.

Why should companies and other organisations be concerned about privacy risks?

Privacy risks may have serious consequences for an organisation, such as:

  • perceived harm to privacy;
  • a failure to meet public expectations on both the use and protection of personal information;
  • retrospective imposition of regulatory conditions;
  • low adoption rates or poor participation in the scheme from both the public and partner organisations;
  • the costs of redesigning the system or retro-fitting solutions;
  • failure of a project or completed system;
  • withdrawal of support from key supporting organisations due to perceived privacy harms; and/ or
  • failure to comply with the law, leading to enforcement action from the regulator or compensation claims from individuals.

(Source: http://ico.org.uk/pia_handbook_html_v2/html/1-Chap2-2.html)


The Top 10 Privacy Risk list is developed by a team of volunteers. The primary contributors to date have been:

  • Stefan Burgmair
  • R. Jason Cronk
  • Edward Delaporte
  • Tim Gough
  • Prof. Hans-Joachim Hof
  • Lukasz Olejnik
  • Florian Stahl



What does this OWASP project offer you?
What releases are available for this project?
what is this project?
Name: OWASP Top 10 Privacy Risks Project (home page)
Purpose: "The deliverable of the project will be a PDF document or web site with a list of the top 10 privacy risks in web applications and possible counter-measures. The goal is to develop a top 10 list for privacy risks in web applications to raise the awareness for this issue and enable the responsible persons to handle personal data in a more responsible way.

The list will cover technological and organizational aspects like missing data encryption or the lack of transparency."

License: GNU GPL v3 License
who is working on this project?
Project Leader(s):
  • Florian Stahl @
  • Stefan Burgmair @
how can you learn more?
Project Pamphlet: Not Yet Created
Project Presentation:
Mailing list: Mailing List Archives
Project Roadmap: View
Key Contacts
  • Contact Florian Stahl @ to contribute to this project
  • Contact Florian Stahl @ to review or sponsor this project
  • Contact the GPC to report a problem or concern about this project or to update information.
current release
Not Yet Published
last reviewed release
Not Yet Reviewed

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