The product does not correctly convert an object, resource, or structure from one type to a different type.
View on MITRENo mitigation information available for this CWE.
No detection method information available for this CWE.
In this example, depending on the return value of accecssmainframe(), the variable amount can hold a negative value when it is returned. Because the function is declared to return an unsigned value, amount will be implicitly cast to an unsigned number.
If the return value of accessmainframe() is -1, then the return value of readdata() will be 4,294,967,295 on a system that uses 32-bit integers.
unsigned int readdata () {int amount = 0;...amount = accessmainframe();...return amount;}The following code uses a union to support the representation of different types of messages. It formats messages differently, depending on their type.
The code intends to process the message as a NAME_TYPE, and sets the default message to "Hello World." However, since both buf.name and buf.nameID are part of the same union, they can act as aliases for the same memory location, depending on memory layout after compilation.
#define NAME_TYPE 1#define ID_TYPE 2 struct MessageBuffer{int msgType;union {char *name;int nameID;};}; int main (int argc, char **argv) { struct MessageBuffer buf;char *defaultMessage = "Hello World"; buf.msgType = NAME_TYPE;buf.name = defaultMessage;printf("Pointer of buf.name is %p\n", buf.name); /* This particular value for nameID is used to make the code architecture-independent. If coming from untrusted input, it could be any value. */ buf.nameID = (int)(defaultMessage + 1);printf("Pointer of buf.name is now %p\n", buf.name);if (buf.msgType == NAME_TYPE) {printf("Message: %s\n", buf.name);}else {printf("Message: Use ID %d\n", buf.nameID);} }Chain: in a web browser, an unsigned 64-bit integer is forcibly cast to a 32-bit integer (CWE-681) and potentially leading to an integer overflow (CWE-190). If an integer overflow occurs, this can cause heap memory corruption (CWE-122)
View DetailsChain: data visualization program written in PHP uses the "!=" operator instead of the type-strict "!==" operator (CWE-480) when validating hash values, potentially leading to an incorrect type conversion (CWE-704)
View DetailsAdditional facts reviewed against primary or authoritative security sources.
Documented detection approaches include Fuzzing; recorded impacts include Other; observed examples include CVE-2021-43537, and CVE-2022-3979. Use these source-defined anchors to turn CWE-704 into implementation, review, and verification checks for the affected component.
CWE-704: Incorrect Type Conversion or Cast — MITRE CWEUse NIST SSDF practices to make prevention of CWE-704, Incorrect Type Conversion or Cast, 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 TechnologyUse CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-704, Incorrect Type Conversion or Cast, 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 AgencyApply MITRE's full root-cause mapping guidance when using CWE-704, Incorrect Type Conversion or Cast. 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 CWEApply MITRE's root-cause mapping quick tips to CWE-704, Incorrect Type Conversion or Cast. 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 CWECWE-704: Incorrect Type Conversion or Cast is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product does not correctly convert an object, resource, or structure from one type to a different type.
If exploited, CWE-704 (Incorrect Type Conversion or Cast) it can compromise Other, leading to outcomes such as Other.
CWE-704 commonly affects C, C++, Not Language-Specific and Memory-Unsafe. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.
MITRE documents real CVEs mapped to CWE-704, including CVE-2021-43537 and CVE-2022-3979. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.
A CWE (Common Weakness Enumeration) like CWE-704 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.