CWE/SANS TOP 25 Most Dangerous Software Errors

What Errors Are Included in the Top 25 Software Errors?

Click on the CWE ID in any of the listings and you will be directed to the relevant spot in the MITRE CWE site where you will find the following:

  • Ranking of each Top 25 entry,
  • Links to the full CWE entry data,
  • Data fields for weakness prevalence and consequences,
  • Remediation cost,
  • Ease of detection,
  • Code examples,
  • Detection Methods,
  • Attack frequency and attacker awareness
  • Related CWE entries, and
  • Related patterns of attack for this weakness.

Each entry at the Top 25 Software Errors site also includes fairly extensive prevention and remediation steps that developers can take to mitigate or eliminate the weakness.

The CWE Top 25

1CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
2CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
3CWE-20Improper Input Validation
4CWE-200Information Exposure
5CWE-125Out-of-bounds Read
6CWE-89Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')
7CWE-416Use After Free
8CWE-190Integer Overflow or Wraparound
9CWE-352Cross-Site Request Forgery (CSRF)
10CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
11CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
12CWE-787Out-of-bounds Write
13CWE-287Improper Authentication
14CWE-476NULL Pointer Dereference
15CWE-732Incorrect Permission Assignment for Critical Resource
16CWE-434Unrestricted Upload of File with Dangerous Type
17CWE-611Improper Restriction of XML External Entity Reference
18CWE-94Improper Control of Generation of Code ('Code Injection')
19CWE-798Use of Hard-coded Credentials
20CWE-400Uncontrolled Resource Consumption
21CWE-772Missing Release of Resource after Effective Lifetime
22CWE-426Untrusted Search Path
23CWE-502Deserialization of Untrusted Data
24CWE-269Improper Privilege Management
25CWE-295Improper Certificate Validation

Resources to Help Eliminate The Top 25 Software Errors

  1. SANS Application Security Courses

    The SANS application security curriculum seeks to ingrain security into the minds of every developer in the world by providing world-class educational resources to design, develop, procure, deploy, and manage secure software. The application security faculty are real-world practitioners with decades of application security experience. The concepts covered in our courses will be applicable to your software security program the day you return to work:

    SANS maintains an Application Security CyberTalent Assessment that measures secure coding skills and allow programmers to determine gaps in their knowledge of secure coding and allows buyers to ensure outsourced programmers have sufficient programming skills. Organizations can learn more at

  2. Developer Security Awareness Training

    The SANS Security Awareness Developer product provides pinpoint software security awareness training on demand, all from the comfort of your desk. Application security awareness training includes over 30+ modules averaging 7-10 minutes in length to maximize learner engagement and retention. The modules cover the full breadth and depth of topics for PCI Section 6.5 compliance and the items that are important for secure software development.

  3. The TOP 25 Errors List will be updated regularly and will be posted at both the SANS and MITRE sites
    CWE Top 25 Software Errors Site

    MITRE maintains the CWE (Common Weakness Enumeration) web site, with the support of the US Department of Homeland Security's National Cyber Security Division, presenting detailed descriptions of the top 25 Software errors along with authoritative guidance for mitigating and avoiding them. That site also contains data on more than 700 additional Software errors, design errors and architecture errors that can lead to exploitable vulnerabilities. CWE Web Site

  4. SAFECode - The Software Assurance Forum for Excellence in Code (members include EMC, Juniper, Microsoft, Nokia, SAP and Symantec) has produced two excellent publications outlining industry best practices for software assurance and providing practical advice for implementing proven methods for secure software development.

    Fundamental Practices for Secure Software Development 3rd Edition

    Overview of Software Integrity Controls

    Framework for Software Supply Chain Integrity

    Fundamental Practices for Secure Software Development

    Software Assurance: An Overview of Current Industry Best Practices

  5. Software Assurance Community Resources Site and DHS web sites

    As part of DHS risk mitigation efforts to enable greater resilience of cyber assets, the Software Assurance Program seeks to reduce software vulnerabilities, minimize exploitation, and address ways to routinely acquire, develop and deploy reliable and trustworthy software products with predictable execution, and to improve diagnostic capabilities to analyze systems for exploitable weaknesses.

  6. Nearly a dozen software companies offer automated tools that test programs for these errors.

How Important Are the Top 25 Software Errors?

We asked several of the participants why they thought this effort was important enough to merit a significant amount of their time and expertise. Here are a few of their answers. More are at the end of the announcement.
Just wanted to commend the depth of the CWE/SANS Top 25. The code examples are particularly excellent. I have asked all my developers to read one of these each day for the next 25 days. I'm taking my own advice as well, and even though I'm still reading some of the "easy" ones (like SQL injection), I still find that I am learning new things about old topics.
Mark E. Haase
- OpenFISMA Project Manager, Endeavor Systems, Inc.
The Top 25 provides much needed guidance for software developers focusing on eliminating software security defects in their products. If you're involved with software development at your organization and are looking to improve your product security posture, you need to read this.
Robert Auger
- Co Founder of The Web Application Security Consortium
It's great to see the CWE/SANS Top 25 list continue to be maintained and mature. Relentlessly spreading the word about the most common security defects in programming is a vital need. The state of security in our software would without a doubt be much improved if everyone who touches software development reads and thoroughly understands this. Kudos.
Kenneth R. van Wyk
- KRvW Associates, LLC

    Contributors to the "CWE/SANS Top 25 Most Dangerous Software Errors":

    • Mark J. Cox, Red Hat Inc.
    • Carsten Eiram, Secunia (Denmark)
    • Pascal Meunier, CERIAS, Purdue University
    • Razak Ellafi & Olivier Bonsignour, CAST Software
    • David Maxwell, NetBSD
    • Cassio Goldschmidt & Mahesh Saptarshi, Symantec Corporation
    • Chris Eng, Veracode, Inc.
    • Paul Anderson, Grammatech Inc.
    • Masato Terada, Information-Technology Promotion Agency (IPA) (Japan)
    • Bernie Wong, IBM
    • Dennis Seymour, Ellumen, Inc.
    • Kent Landfield,  McAfee
    • Hart Rossman, SAIC
    • Jeremy Epstein, SRI International
    • Matt Bishop, UC Davis
    • Adam Hahn & Sean Barnum, MITRE
    • Jeremiah Grossman, White Hat Security
    • Kenneth van Wyk, KRvW Associates
    • Bruce Lowenthal, Oracle Corporation
    • Jacob West, Fortify Software, an HP Company
    • Frank Kim, ThinkSec
    • Christian Heinrich, (Australia)
    • Ketan Vyas, Tata Consultancy Services (TCS)
    • Joe Baum, Motorola Solutions
    • Matthew Coles, Aaron Katz & Nazira Omuralieva, RSA, the Security Division of EMC
    • National Security Agency (NSA) Information Assurance Division
    • Department of Homeland Security (DHS) National Cyber Security Division

    The following individuals and organizations aided in the development of the Top 25 through their input to the CWSS/CWRAF


    • Bruce Lowenthal, Oracle
    • Damir (Gaus) Rajnovic, Cisco
    • Stephen Chasko
    • Chris Eng and Chris Wysopal, Veracode
    • Casper Jones
    • Edward Luck and Martin Tan, Dimension Data (Australia)
    • James Jardine, Jardine Software
    • Jon Zucker, Cenzic
    • Jason Liu, Northrop Grumman
    • Ory Segal, IBM
    • Mahi Dontamsetti, DTCC
    • Hart Rossman, SAIC
    • OWASP
    • EC-Council

    Version 3.0 Updated June 27, 2011