Improper Handling of Case Sensitivity

The software does not properly account for differences in case sensitivity when accessing or determining the properties of a resource, leading to inconsistent results.


Improperly handled case sensitive data can lead to several possible consequences, including:

case-insensitive passwords reducing the size of the key space, making brute force attacks easier

bypassing filters or access controls using alternate names

multiple interpretation errors using alternate names.


The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.

Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.

Example One

In the following example, an XSS neutralization method replaces script tags in user supplied input with a safe equivalent:

public String preventXSS(String input, String mask) {
  return input.replaceAll("script", mask);

The code only works when the "script" tag is in all lower-case, forming an incomplete denylist (CWE-184). Equivalent tags such as "SCRIPT" or "ScRiPt" will not be neutralized by this method, allowing an XSS attack.

See Also

SFP Secondary Cluster: Faulty Input Transformation

This category identifies Software Fault Patterns (SFPs) within the Faulty Input Transformation cluster.

Data Processing Errors

Weaknesses in this category are typically found in functionality that processes data. Data processing is the manipulation of input to retrieve or save information.

Comprehensive CWE Dictionary

This view (slice) covers all the elements in CWE.

Weaknesses without Software Fault Patterns

CWE identifiers in this view are weaknesses that do not have associated Software Fault Patterns (SFPs), as covered by the CWE-888 view. As such, they represent gaps in...

Weaknesses Introduced During Implementation

This view (slice) lists weaknesses that can be introduced during implementation.

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