What is SANS Top 25?
The SANS Top 25 (formally the CWE/SANS Top 25 Most Dangerous Software Errors) is a list of the most widespread and critical weaknesses that lead to serious vulnerabilities in software. Originally developed as a collaboration between the SANS Institute and MITRE Corporation, the list is now maintained by MITRE as part of the CWE program.
Relationship to CWE Top 25
The SANS Top 25 evolved into the CWE Top 25 Most Dangerous Software Weaknesses. While the SANS branding persists in industry discussions, the current authoritative list is published by MITRE as the CWE Top 25, updated annually based on real-world vulnerability data from the National Vulnerability Database.
Current Top Weaknesses
The most dangerous weaknesses consistently include:
Memory safety issues:
- CWE-787: Out-of-bounds Write
- CWE-125: Out-of-bounds Read
- CWE-416: Use After Free
- CWE-476: NULL Pointer Dereference
Injection vulnerabilities:
- CWE-79: Cross-site Scripting (XSS)
- CWE-89: SQL Injection
- CWE-78: OS Command Injection
Access control failures:
- CWE-862: Missing Authorization
- CWE-863: Incorrect Authorization
- CWE-306: Missing Authentication for Critical Function
Data handling issues:
- CWE-20: Improper Input Validation
- CWE-22: Path Traversal
- CWE-352: Cross-Site Request Forgery (CSRF)
How rankings are determined
MITRE calculates the Top 25 using a formula that considers:
- Frequency: How often the weakness appears in CVE records
- Severity: Average CVSS scores of associated vulnerabilities
- Exploitability: Real-world exploitation data
This data-driven approach differs from the OWASP Top 10, which uses broader input including surveys and expert judgment.
SANS Top 25 vs OWASP Top 10
| SANS/CWE Top 25 | OWASP Top 10 |
|---|---|
| 25 specific weakness types | 10 broad risk categories |
| Based on CVE/NVD data | Based on industry surveys + data |
| Maps directly to CWE IDs | References CWE but higher abstraction |
| Language-agnostic weaknesses | Web application focus |
| Updated annually | Updated every 3-4 years |
The two lists are complementary. OWASP provides high-level categories for awareness; SANS/CWE provides specific technical weaknesses for tool development and detailed guidance.
Using the SANS Top 25
Security tool configuration: SAST and AI code review tools use CWE/SANS Top 25 as a baseline ruleset. Enabling detection for these weaknesses provides coverage of the most exploited vulnerability patterns.
Procurement requirements: Organizations specify SANS Top 25 coverage when evaluating security tools or vendor software.
Training prioritization: Developer training programs focus on weaknesses that appear in the Top 25, maximizing security improvement per training hour.
Compliance mapping: Security frameworks often reference the SANS Top 25 when specifying secure coding requirements.
See also: CWE, OWASP Top 10, CVE, SAST
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