CWE-704: Incorrect Type Conversion or Cast

cwe.mitre.org • September 8, 2026

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.

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.

As a result, modification of buf.nameID - an int - can effectively modify the pointer that is stored in buf.name - a string.

Execution of the program might generate output such as:

Pointer of name is 10830 Pointer of name is now 10831 Message: ello World

Notice how the pointer for buf.name was changed, even though buf.name was not explicitly modified.

In this case, the first "H" character of the message is omitted. However, if an attacker is able to fully control the value of buf.nameID, then buf.name could contain an arbitrary pointer, leading to out-of-bounds reads or writes.

Note: this is a curated list of examples for users to understand the variety of ways in which this weakness can be introduced. It is not a complete list of all CVEs that are related to this CWE entry.

The full story

This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Multiple CVEs Disclosed on September 8, 2026, Affecting Microsoft Products On September 8, 2026, multiple CVEs were disclosed affecting various Microsoft products, including SharePoint and Office. Key vulnerabilities include improper access controls, buffer overflows, and command injections, which could allow unauthorized code execution and information disclosure. CVE-2026-85880, noted for active exploitation, was added to CISA's KEV list on the same day. Other vulnerabilities, such as CVE-2026-69428 and CVE-2026-69621, also pose significant risks due to their potential for exploitation. Organizations using affected versions of Microsoft products are urged to apply patches immediately to mitigate risks. The vulnerabilities impact a range of systems, including SharePoint Server and Microsoft Office, and could lead to severe consequences if exploited. 927 sources 74

Extracted Entities

CWE Weaknesses (3)

Cwe-125 - Out-of-bounds Read CWE-704 - Incorrect Type Conversion or Cast Cwe-787 - Out-of-bounds Write

Domains (1)

buf.name