CWE-205: Observable Behavioral Discrepancy

BaseIncomplete

The product's behaviors indicate important differences that may be observed by unauthorized actors in a way that reveals (1) its internal state or decision process, or (2) differences from other products with equivalent functionality.

View on MITRE
Back to CWE Lookup

Extended Description

Ideally, a product should provide as little information about its internal operations as possible. Otherwise, attackers could use knowledge of these internal operations to simplify or optimize their attack. In some cases, behavioral discrepancies can be used by attackers to form a side channel.

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-205 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-205, Observable Behavioral 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 Framework — National Institute of Standards and Technology

Make elimination of CWE-205 a product outcome

Apply CISA's Secure by Design principle of taking ownership of customer security outcomes to CWE-205, Observable Behavioral Discrepancy. Put the weakness in the product threat model and security roadmap, fund class-level design and platform changes, prefer safe defaults and reusable guardrails, and publish measurable progress. Do not transfer the primary burden to customer configuration when the manufacturer can remove or contain the root cause in the product.

Shifting the Balance of Cybersecurity Risk: Secure by Design Software — Cybersecurity and Infrastructure Security Agency

Connect Observable Behavioral Discrepancy to documented attack evidence

Recorded impacts include Read Application Data, and Bypass Protection Mechanism; the entry maps to CAPEC-541, and CAPEC-580; observed examples include CVE-2002-0208, and CVE-2004-2252. Use these source-defined anchors to turn CWE-205 into implementation, review, and verification checks for the affected component.

CWE-205: Observable Behavioral Discrepancy — MITRE CWE

Apply precise root-cause mapping to CWE-205

Apply MITRE's full root-cause mapping guidance when using CWE-205, Observable Behavioral 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 Guidance — MITRE CWE

Validate CWE-205 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-205, Observable Behavioral 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 Tips — MITRE CWE

Frequently Asked Questions

What is CWE-205: Observable Behavioral Discrepancy?+

CWE-205: Observable Behavioral Discrepancy is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product's behaviors indicate important differences that may be observed by unauthorized actors in a way that reveals (1) its internal state or decision process, or (2) differences from other products with equivalent functionality. Ideally, a product should provide as little information about its internal operations as possible. Otherwise, attackers could use knowledge of these internal operations to simplify or optimize their attack. In some cases, behavioral discrepancies can be used by attackers to form a side channel.

What are the security consequences of Observable Behavioral Discrepancy?+

If exploited, CWE-205 (Observable Behavioral 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 Behavioral Discrepancy?+

CWE-205 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 Behavioral Discrepancy?+

MITRE documents real CVEs mapped to CWE-205, including CVE-2002-0208 and CVE-2004-2252. 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-205 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.

Learn More

Find Related CVEs

Search for vulnerabilities that exploit CWE-205

CVE vs CWE: What's the Difference?

Understanding vulnerabilities vs weaknesses

Understanding CVSS Scoring

How vulnerability severity is measured

View Full MITRE Entry

Complete technical details and references

Advertisement