CWE-42: Path Equivalence: 'filename.' (Trailing Dot)

VariantIncomplete

The product accepts path input in the form of trailing dot ('filedir.') without appropriate validation, which can lead to ambiguous path resolution and allow an attacker to traverse the file system to unintended locations or access arbitrary files.

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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-42 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-42, Path Equivalence: 'filename.' (Trailing Dot), 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

Make elimination of CWE-42 a product outcome

Apply CISA's Secure by Design principle of taking ownership of customer security outcomes to CWE-42, Path Equivalence: 'filename.' (Trailing Dot). 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 SoftwareCybersecurity and Infrastructure Security Agency

Connect Path Equivalence: 'filename.' (Trailing Dot) to documented attack evidence

Recorded impacts include Bypass Protection Mechanism; observed examples include CVE-2000-1114, CVE-2002-1986, and CVE-2004-2213; related weaknesses include CWE-41, and CWE-162. Use these source-defined anchors to turn CWE-42 into implementation, review, and verification checks for the affected component.

CWE-42: Path Equivalence: 'filename.' (Trailing Dot)MITRE CWE

Apply precise root-cause mapping to CWE-42

Apply MITRE's full root-cause mapping guidance when using CWE-42, Path Equivalence: 'filename.' (Trailing Dot). 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-42 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-42, Path Equivalence: 'filename.' (Trailing Dot). 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-42: Path Equivalence: 'filename.' (Trailing Dot)?+

CWE-42: Path Equivalence: 'filename.' (Trailing Dot) is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product accepts path input in the form of trailing dot ('filedir.') without appropriate validation, which can lead to ambiguous path resolution and allow an attacker to traverse the file system to unintended locations or access arbitrary files.

What are the security consequences of Path Equivalence: 'filename.' (Trailing Dot)?+

If exploited, CWE-42 (Path Equivalence: 'filename.' (Trailing Dot)) it can compromise Access Control, leading to outcomes such as Bypass Protection Mechanism.

Which programming languages are affected by Path Equivalence: 'filename.' (Trailing Dot)?+

CWE-42 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 Path Equivalence: 'filename.' (Trailing Dot)?+

MITRE documents real CVEs mapped to CWE-42, including CVE-2000-1114, CVE-2002-1986, CVE-2004-2213, CVE-2005-3293 and CVE-2004-0061. 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-42 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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