Tag Archives: Improper Handling of Missing Special Element

CWE-166 – Improper Handling of Missing Special Element

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Description

The software receives input from an upstream component, but it does not handle or incorrectly handles when an expected special element is missing.

Modes of Introduction:

– Implementation

 

 

Related Weaknesses

CWE-159
CWE-703

 

Consequences

Availability: DoS: Crash, Exit, or Restart

 

Potential Mitigations

Phase:

Description: 

Developers should anticipate that special elements will be removed in the input vectors of their software system. Use an appropriate combination of denylists and allowlists to ensure only valid, expected and appropriate input is processed by the system.

Phase: Implementation

Description: 

Phase: Implementation

Description: 

Inputs should be decoded and canonicalized to the application’s current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.

CVE References

  • CVE-2002-1362
    • Crash via message type without separator character
  • CVE-2002-0729
    • Missing special character (separator) causes crash
  • CVE-2002-1532
    • HTTP GET without rnrn CRLF sequences causes product to wait indefinitely and prevents other users from accessing it