Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
CWE-192 Variant Incomplete
Integer Coercion Error
An integer coercion error occurs when a program incorrectly converts, extends, or truncates a number between different data types, leading to unexpected values.
Definition
What is CWE-192?
An integer coercion error occurs when a program incorrectly converts, extends, or truncates a number between different data types, leading to unexpected values.
These errors happen during operations like type casting or when moving values between different-sized integers (e.g., from a short to a long). While they often cause crashes or corrupt data, they can also create subtle logic flaws. For example, a miscalculated size check might later enable a buffer overflow, turning a data integrity issue into a serious security vulnerability.
Managing this at scale is difficult; an ASPM like Plexicus can help you track and remediate these flaws across your entire stack. While SAST tools catch the pattern, Plexicus uses AI to suggest the actual code fix, saving hours of manual work by pinpointing the risky type conversions and providing corrected code snippets.
Real-world impact
Real-world CVEs caused by CWE-192
-
Chain: integer coercion error (CWE-192) prevents a return value from indicating an error, leading to out-of-bounds write (CWE-787)
How attackers exploit it
Step-by-step attacker path
- 1
The following code is intended to read an incoming packet from a socket and extract one or more headers.
- 2
The code performs a check to make sure that the packet does not contain too many headers. However, numHeaders is defined as a signed int, so it could be negative. If the incoming packet specifies a value such as -3, then the malloc calculation will generate a negative number (say, -300 if each header can be a maximum of 100 bytes). When this result is provided to malloc(), it is first converted to a size_t type. This conversion then produces a large value such as 4294966996, which may cause malloc() to fail or to allocate an extremely large amount of memory (CWE-195). With the appropriate negative numbers, an attacker could trick malloc() into using a very small positive number, which then allocates a buffer that is much smaller than expected, potentially leading to a buffer overflow.
- 3
The following code reads a maximum size and performs validation on that size. It then performs a strncpy, assuming it will not exceed the boundaries of the array. While the use of "short s" is forced in this particular example, short int's are frequently used within real-world code, such as code that processes structured data.
- 4
This code first exhibits an example of CWE-839, allowing "s" to be a negative number. When the negative short "s" is converted to an unsigned integer, it becomes an extremely large positive integer. When this converted integer is used by strncpy() it will lead to a buffer overflow (CWE-119).
Vulnerable code example
Vulnerable C
The following code is intended to read an incoming packet from a socket and extract one or more headers.
DataPacket *packet;
int numHeaders;
PacketHeader *headers;
sock=AcceptSocketConnection();
ReadPacket(packet, sock);
numHeaders =packet->headers;
if (numHeaders > 100) {
ExitError("too many headers!");
}
headers = malloc(numHeaders * sizeof(PacketHeader);
ParsePacketHeaders(packet, headers); Secure code example
Secure pseudo
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
const safe = validateAndEscape(input);
return executeWithGuards(safe);
} What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist
How to prevent CWE-192
- Requirements A language which throws exceptions on ambiguous data casts might be chosen.
- Architecture and Design Design objects and program flow such that multiple or complex casts are unnecessary
- Implementation Ensure that any data type casting that you must used is entirely understood in order to reduce the plausibility of error in use.
Detection signals
How to detect CWE-192
CWE-192
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Frequently asked questions What is CWE-192?
How serious is CWE-192?
What languages or platforms are affected by CWE-192?
How can I prevent CWE-192?
How does Plexicus detect and fix CWE-192?
Where can I learn more about CWE-192?
Frequently asked questions
What is CWE-192?
An integer coercion error occurs when a program incorrectly converts, extends, or truncates a number between different data types, leading to unexpected values.
How serious is CWE-192?
MITRE rates the likelihood of exploit as Medium — exploitation is realistic but typically requires specific conditions.
What languages or platforms are affected by CWE-192?
MITRE lists the following affected platforms: C, C++, Java, C#.
How can I prevent CWE-192?
A language which throws exceptions on ambiguous data casts might be chosen. Design objects and program flow such that multiple or complex casts are unnecessary
How does Plexicus detect and fix CWE-192?
Plexicus's SAST engine matches the data-flow signature for CWE-192 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.
Where can I learn more about CWE-192?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/192.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-192
CWE-681 Parent
Incorrect Conversion between Numeric Types
This vulnerability occurs when a program converts a value from one numeric type to another (like a 64-bit integer to a 32-bit integer) and…
CWE-194 Sibling
Unexpected Sign Extension
This vulnerability occurs when a signed number from a smaller data type is moved or cast to a larger type, causing its sign bit to be…
CWE-195 Sibling
Signed to Unsigned Conversion Error
This vulnerability occurs when a signed integer (which can hold negative values) is converted to an unsigned integer (which holds only…
CWE-196 Sibling
Unsigned to Signed Conversion Error
This vulnerability occurs when a program takes an unsigned integer and converts it directly to a signed integer. If the original unsigned…
CWE-197 Sibling
Numeric Truncation Error
A numeric truncation error happens when a program converts a number to a smaller data type, cutting off its higher-order bits and…
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