CWE-703: Improper Check or Handling of Exceptional Conditions

Code Examples & CVEs

Demonstrative Examples

Consider the following code segment:

The programmer expects that when fgets() returns, buf will contain a null-terminated string of length 9 or less. But if an I/O error occurs, fgets() will not null-terminate buf. Furthermore, if the end of the file is reached before any characters are read, fgets() returns without writing anything to buf. In both of these situations, fgets() signals that something unusual has happened by returning NULL, but in this code, the warning will not be noticed. The lack of a null terminator in buf can result in a buffer overflow in the subsequent call to strcpy().

BadC

char buf[10], cp_buf[10];fgets(buf, 10, stdin);strcpy(cp_buf, buf);

The following method throws three types of exceptions.

While it might seem tidier to write

GoodJava

public void doExchange() throws IOException, InvocationTargetException, SQLException {...}

The following method throws three types of exceptions.

While it might seem tidier to write

BadJava

public void doExchange() throws Exception {...}

Observed CVE Examples (2)

[REF-1374]

Chain: JavaScript-based cryptocurrency library can fall back to the insecure Math.random() function instead of reporting a failure (CWE-392), thus reducing the entropy (CWE-332) and leading to generation of non-unique cryptographic keys for Bitcoin wallets (CWE-1391)

View Details

CVE-2022-22224

Chain: an operating system does not properly process malformed Open Shortest Path First (OSPF) Type/Length/Value Identifiers (TLV) (CWE-703), which can cause the process to enter an infinite loop (CWE-835)

View Details

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Detect Improper Check or Handling of Exceptional Conditions with Dynamic Analysis with Manual Results Interpretation

Documented detection approaches include Dynamic Analysis with Manual Results Interpretation, Manual Static Analysis - Source Code, Automated Static Analysis - Source Code, and Architecture or Design Review; recorded impacts include Read Application Data, DoS: Crash, Exit, or Restart, and Unexpected State; observed examples include CVE-2022-22224. Use these source-defined anchors to turn CWE-703 into implementation, review, and verification checks for the affected component.

CWE-703: Improper Check or Handling of Exceptional Conditions — MITRE CWE

Prevent CWE-703 through an SSDF control plan

Use NIST SSDF practices to make prevention of CWE-703, Improper Check or Handling of Exceptional Conditions, 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-703 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-703, Improper Check or Handling of Exceptional Conditions, 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-703

Apply MITRE's full root-cause mapping guidance when using CWE-703, Improper Check or Handling of Exceptional Conditions. 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-703 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-703, Improper Check or Handling of Exceptional Conditions. 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-703: Improper Check or Handling of Exceptional Conditions?+

CWE-703: Improper Check or Handling of Exceptional Conditions is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product does not properly anticipate or handle exceptional conditions that rarely occur during normal operation of the product.

What are the security consequences of Improper Check or Handling of Exceptional Conditions?+

If exploited, CWE-703 (Improper Check or Handling of Exceptional Conditions) it can compromise Confidentiality, Availability and Integrity, leading to outcomes such as Read Application Data, DoS: Crash, Exit, or Restart and Unexpected State.

How is Improper Check or Handling of Exceptional Conditions detected?+

CWE-703 can be detected using Dynamic Analysis with Manual Results Interpretation, Manual Static Analysis - Source Code, Automated Static Analysis - Source Code and Architecture or Design Review. Combining automated tooling with manual review typically yields the best coverage.

Which programming languages are affected by Improper Check or Handling of Exceptional Conditions?+

CWE-703 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 Improper Check or Handling of Exceptional Conditions?+

MITRE documents real CVEs mapped to CWE-703, including [REF-1374] and CVE-2022-22224. 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-703 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-703: Improper Check or Handling of Exceptional Conditions

Technical Details

Applicable To

Security Consequences

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Impact

Mitigation Strategies

Detection Methods

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Effectiveness

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Code Examples & CVEs

Demonstrative Examples

Observed CVE Examples (2)

CWE Relationships

Source-backed guidance

Detect Improper Check or Handling of Exceptional Conditions with Dynamic Analysis with Manual Results Interpretation

Prevent CWE-703 through an SSDF control plan

Triage CWE-703 against known exploitation evidence

Apply precise root-cause mapping to CWE-703

Validate CWE-703 with root-cause mapping checks

Frequently Asked Questions

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