Base weakness

Draft

CWE-450: Multiple Interpretations of UI Input

The UI has multiple interpretations of user input but does not prompt the user when it selects the less secure interpretation.

Last updated May 1, 2026

3

Recorded CVEs

With this primary weakness

0

KEVs

In the CISA KEV catalog

Not rated

Likelihood of exploit

Per MITRE

Base

Abstraction

MITRE classification

Overview

CWE-450 (Multiple Interpretations of UI Input) is a base-level software weakness catalogued by MITRE in the Common Weakness Enumeration (CWE). It describes a recurring type of mistake that can lead to exploitable security vulnerabilities.

Real-world CVEs

3 recorded CVEs are caused by CWE-450 (Multiple Interpretations of UI Input). The highest-severity and most recent are shown first.

Common consequences

What can happen when CWE-450 is exploited.

Varies by Context

Affects: Other

How it happens

When it is introduced

Typically introduced during these phases of the software lifecycle.

Implementation

How to prevent it

Practical mitigations for CWE-450, grouped by where in the lifecycle they apply.

Implementation

Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.

When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."

Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

Implementation

Input Validation

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.

Terminology & mappings

Mapped taxonomies

PLOVER: Multiple Interpretations of UI Input

Frequently asked questions

Common questions about CWE-450.

What is CWE-450?

The UI has multiple interpretations of user input but does not prompt the user when it selects the less secure interpretation.

What CVEs are caused by CWE-450?

3 recorded CVEs are attributed to CWE-450, including CVE-2024-25858, CVE-2022-20863, CVE-2021-1242.

How do you prevent CWE-450?

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.

What are the consequences of CWE-450?

Exploiting CWE-450 can lead to: Varies by Context.

Is CWE-450 actively exploited?

3 recorded CVEs are caused by CWE-450; none are currently in CISA's KEV catalog of actively exploited flaws.

References

Weakness data is sourced from the MITRE CWE catalog (v4.20). CVE associations are aggregated and kept current by RadicalNotion.AI.

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Overview

Real-world CVEs

Common consequences

How it happens

When it is introduced

How to prevent it

Related weaknesses

Parent

Terminology & mappings

Mapped taxonomies

Frequently asked questions

What is CWE-450?

What CVEs are caused by CWE-450?

How do you prevent CWE-450?

What are the consequences of CWE-450?

Is CWE-450 actively exploited?

References

Stay ahead of CWE-450