CWE-636: Not Failing Securely ('Failing Open')

ClassDraft

When the product encounters an error condition or failure, its design requires it to fall back to a state that is less secure than other options that are available, such as selecting the weakest encryption algorithm or using the most permissive access control restrictions.

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Extended Description

By entering a less secure state, the product inherits the weaknesses associated with that state, making it easier to compromise. At the least, it causes administrators to have a false sense of security. This weakness typically occurs as a result of wanting to "fail functional" to minimize administration and support costs, instead of "failing safe."

Technical Details

Structure
Simple

Applicable To

Languages
Not Language-Specific
Platforms

Frequently Asked Questions

What is CWE-636: Not Failing Securely ('Failing Open')?+

CWE-636: Not Failing Securely ('Failing Open') is a Common Weakness Enumeration (CWE) entry maintained by MITRE. When the product encounters an error condition or failure, its design requires it to fall back to a state that is less secure than other options that are available, such as selecting the weakest encryption algorithm or using the most permissive access control restrictions. By entering a less secure state, the product inherits the weaknesses associated with that state, making it easier to compromise. At the least, it causes administrators to have a false sense of security. This weakness typically occurs as a result of wanting to "fail functional" to minimize administration and support costs, instead of "failing safe."

What are the security consequences of Not Failing Securely ('Failing Open')?+

If exploited, CWE-636 (Not Failing Securely ('Failing Open')) it can compromise Access Control, leading to outcomes such as Bypass Protection Mechanism.

How do you prevent or mitigate Not Failing Securely ('Failing Open')?+

Recommended mitigations for CWE-636 include: Subdivide and allocate resources and components so that a failure in one part does not affect the entire product.

Which programming languages are affected by Not Failing Securely ('Failing Open')?+

CWE-636 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What are real-world examples of Not Failing Securely ('Failing Open')?+

MITRE documents real CVEs mapped to CWE-636, including CVE-2007-5277 and CVE-2006-4407. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-636 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

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