CWE-203: Observable Discrepancy

BaseIncomplete

The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.

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Technical Details

Structure
Simple
Vulnerability Mapping
ALLOWED

Applicable To

Languages
Not Language-Specific
Platforms

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-203 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-203, Observable Discrepancy, throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development FrameworkNational Institute of Standards and Technology

Apply Separation of Privilege controls for Observable Discrepancy

MITRE associates mitigation with Architecture and Design, and Implementation; the listed strategies include Separation of Privilege; recorded impacts include Read Application Data, and Bypass Protection Mechanism. Use these source-defined anchors to turn CWE-203 into implementation, review, and verification checks for the affected component.

CWE-203: Observable DiscrepancyMITRE CWE

Triage CWE-203 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-203, Observable Discrepancy, has evidence of exploitation in the wild. Confirm the CVE-to-CWE root-cause mapping independently before attaching the example, then capture the affected product, required action, and remediation deadline. A missing KEV match is not evidence that the weakness is unexploited, and a KEV entry must not be generalized to every occurrence of this CWE.

Known Exploited Vulnerabilities CatalogCybersecurity and Infrastructure Security Agency

Apply precise root-cause mapping to CWE-203

Apply MITRE's full root-cause mapping guidance when using CWE-203, Observable Discrepancy. Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping GuidanceMITRE CWE

Validate CWE-203 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-203, Observable Discrepancy. Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick TipsMITRE CWE

Frequently Asked Questions

What is CWE-203: Observable Discrepancy?+

CWE-203: Observable Discrepancy is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.

What are the security consequences of Observable Discrepancy?+

If exploited, CWE-203 (Observable Discrepancy) it can compromise Confidentiality and Access Control, leading to outcomes such as Read Application Data and Bypass Protection Mechanism.

Which programming languages are affected by Observable Discrepancy?+

CWE-203 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 Observable Discrepancy?+

MITRE documents real CVEs mapped to CWE-203, including CVE-2020-8695, CVE-2019-14353, CVE-2019-10071, CVE-2002-2094 and CVE-2001-1483. 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-203 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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