CWE-303: Incorrect Implementation of Authentication Algorithm

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-303 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-303, Incorrect Implementation of Authentication Algorithm, 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-303 a product outcome

Apply CISA's Secure by Design principle of taking ownership of customer security outcomes to CWE-303, Incorrect Implementation of Authentication Algorithm. 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 Incorrect Implementation of Authentication Algorithm to documented attack evidence

Recorded impacts include Bypass Protection Mechanism; the entry maps to CAPEC-90; observed examples include CVE-2003-0750. Use these source-defined anchors to turn CWE-303 into implementation, review, and verification checks for the affected component.

CWE-303: Incorrect Implementation of Authentication Algorithm — MITRE CWE

Apply precise root-cause mapping to CWE-303

Apply MITRE's full root-cause mapping guidance when using CWE-303, Incorrect Implementation of Authentication Algorithm. 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-303 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-303, Incorrect Implementation of Authentication Algorithm. 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-303: Incorrect Implementation of Authentication Algorithm?+

CWE-303: Incorrect Implementation of Authentication Algorithm is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The requirements for the product dictate the use of an established authentication algorithm, but the implementation of the algorithm is incorrect. This incorrect implementation may allow authentication to be bypassed.

What are the security consequences of Incorrect Implementation of Authentication Algorithm?+

If exploited, CWE-303 (Incorrect Implementation of Authentication Algorithm) it can compromise Access Control, leading to outcomes such as Bypass Protection Mechanism.

Which programming languages are affected by Incorrect Implementation of Authentication Algorithm?+

CWE-303 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 Incorrect Implementation of Authentication Algorithm?+

MITRE documents real CVEs mapped to CWE-303, including CVE-2003-0750. 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-303 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.

CWE-303: Incorrect Implementation of Authentication Algorithm

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Impact

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Code Examples & CVEs

Observed CVE Examples (1)

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