CWE-403: Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak')

Extended Description

When a new process is forked or executed, the child process inherits any open file descriptors. When the child process has fewer privileges than the parent process, this might introduce a vulnerability if the child process can access the file descriptor but does not have the privileges to access the associated file.

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Detect Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak') with Automated Static Analysis

Documented detection approaches include Automated Static Analysis; recorded impacts include Read Application Data, and Modify Application Data; observed examples include CVE-2003-0740, CVE-2004-1033, and CVE-2000-0094. Use these source-defined anchors to turn CWE-403 into implementation, review, and verification checks for the affected component.

CWE-403: Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak') — MITRE CWE

Prevent CWE-403 through an SSDF control plan

Use NIST SSDF practices to make prevention of CWE-403, Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak'), an explicit development outcome. Translate the CWE definition into security requirements and design constraints, choose safer implementation patterns and toolchain checks, and define acceptance evidence before release. Feed every confirmed occurrence back into the requirements, design review, and coding rules so the same root cause is removed across the product rather than patched in one location.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Triage CWE-403 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-403, Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak'), 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 Catalog — Cybersecurity and Infrastructure Security Agency

Apply precise root-cause mapping to CWE-403

Apply MITRE's full root-cause mapping guidance when using CWE-403, Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak'). 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-403 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-403, Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak'). 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-403: Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak')?+

CWE-403: Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak') is a Common Weakness Enumeration (CWE) entry maintained by MITRE. A process does not close sensitive file descriptors before invoking a child process, which allows the child to perform unauthorized I/O operations using those descriptors. When a new process is forked or executed, the child process inherits any open file descriptors. When the child process has fewer privileges than the parent process, this might introduce a vulnerability if the child process can access the file descriptor but does not have the privileges to access the associated file.

What are the security consequences of Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak')?+

If exploited, CWE-403 (Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak')) it can compromise Confidentiality and Integrity, leading to outcomes such as Read Application Data and Modify Application Data.

Which programming languages are affected by Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak')?+

CWE-403 commonly affects C and Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What are real-world examples of Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak')?+

MITRE documents real CVEs mapped to CWE-403, including CVE-2003-0740, CVE-2004-1033, CVE-2000-0094, CVE-2002-0638 and CVE-2003-0489. 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-403 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-403: Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak')

Extended Description

Technical Details

Applicable To

Security Consequences

Scope

Impact

Mitigation Strategies

Detection Methods

Code Examples & CVEs

Observed CVE Examples (8)

CWE Relationships

Parent Weaknesses