CWE-190: Integer Overflow or Wraparound

Description

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

Extended Description

N/A

ThreatScore

Threat Mapped score: 0.0

Industry: Finiancial

Threat priority: Unclassified

Observed Examples (CVEs)

CVE: CVE-2025-27363 — KEV

Font rendering library does not properly handle assigning a signed short value to an unsigned long (CWE-195), leading to an integer wraparound (CWE-190), causing too small of a buffer (CWE-131), leading to an out-of-bounds write (CWE-787).
CVE: CVE-2021-43537

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)
CVE: CVE-2022-21668

Chain: Python library does not limit the resources used to process images that specify a very large number of bands (CWE-1284), leading to excessive memory consumption (CWE-789) or an integer overflow (CWE-190).
CVE: CVE-2022-0545

Chain: 3D renderer has an integer overflow (CWE-190) leading to write-what-where condition (CWE-123) using a crafted image.
CVE: CVE-2021-30860 — KEV

Chain: improper input validation (CWE-20) leads to integer overflow (CWE-190) in mobile OS, as exploited in the wild per CISA KEV.
CVE: CVE-2021-30663 — KEV

Chain: improper input validation (CWE-20) leads to integer overflow (CWE-190) in mobile OS, as exploited in the wild per CISA KEV.
CVE: CVE-2018-10887

Chain: unexpected sign extension (CWE-194) leads to integer overflow (CWE-190), causing an out-of-bounds read (CWE-125)
CVE: CVE-2019-1010006

Chain: compiler optimization (CWE-733) removes or modifies code used to detect integer overflow (CWE-190), allowing out-of-bounds write (CWE-787).
CVE: CVE-2010-1866

Chain: integer overflow (CWE-190) causes a negative signed value, which later bypasses a maximum-only check (CWE-839), leading to heap-based buffer overflow (CWE-122).
CVE: CVE-2010-2753

Chain: integer overflow leads to use-after-free
CVE: CVE-2005-1513

Chain: integer overflow in securely-coded mail program leads to buffer overflow. In 2005, this was regarded as unrealistic to exploit, but in 2020, it was rediscovered to be easier to exploit due to evolutions of the technology.
CVE: CVE-2002-0391

Integer overflow via a large number of arguments.
CVE: CVE-2002-0639

Integer overflow in OpenSSH as listed in the demonstrative examples.
CVE: CVE-2005-1141

Image with large width and height leads to integer overflow.
CVE: CVE-2005-0102

Length value of -1 leads to allocation of 0 bytes and resultant heap overflow.
CVE: CVE-2004-2013

Length value of -1 leads to allocation of 0 bytes and resultant heap overflow.
CVE: CVE-2017-1000121

chain: unchecked message size metadata allows integer overflow (CWE-190) leading to buffer overflow (CWE-119).
CVE: CVE-2013-1591

Chain: an integer overflow (CWE-190) in the image size calculation causes an infinite loop (CWE-835) which sequentially allocates buffers without limits (CWE-1325) until the stack is full.

Related Attack Patterns (CAPEC)

CAPEC-92

Attack TTPs

N/A

Modes of Introduction

Phase	Note
Implementation	This weakness may become security critical when determining the offset or size in behaviors such as memory allocation, copying, and concatenation.

Common Consequences

Impact: DoS: Crash, Exit, or Restart, DoS: Resource Consumption (Memory), DoS: Instability — Notes: This weakness can generally lead to undefined behavior and therefore crashes. When the calculated result is used for resource allocation, this weakness can cause too many (or too few) resources to be allocated, possibly enabling crashes if the product requests more resources than can be provided.
Impact: Modify Memory — Notes: If the value in question is important to data (as opposed to flow), simple data corruption has occurred. Also, if the overflow/wraparound results in other conditions such as buffer overflows, further memory corruption may occur.
Impact: Execute Unauthorized Code or Commands, Bypass Protection Mechanism — Notes: This weakness can sometimes trigger buffer overflows, which can be used to execute arbitrary code. This is usually outside the scope of the product's implicit security policy.
Impact: Alter Execution Logic, DoS: Crash, Exit, or Restart, DoS: Resource Consumption (CPU) — Notes: If the overflow/wraparound occurs in a loop index variable, this could cause the loop to terminate at the wrong time - too early, too late, or not at all (i.e., infinite loops). With too many iterations, some loops could consume too many resources such as memory, file handles, etc., possibly leading to a crash or other DoS.
Impact: Bypass Protection Mechanism — Notes: If integer values are used in security-critical decisions, such as calculating quotas or allocation limits, integer overflows can be used to cause an incorrect security decision.

Potential Mitigations

Requirements: Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol. (N/A)
Requirements: Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. If possible, choose a language or compiler that performs automatic bounds checking. (N/A)
Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Use libraries or frameworks that make it easier to handle numbers without unexpected consequences. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++). [REF-106] (N/A)
Implementation: Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range. Use unsigned integers where possible. This makes it easier to perform validation for integer overflows. When signed integers are required, ensure that the range check includes minimum values as well as maximum values. (N/A)
Implementation: Understand the programming language's underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, "not-a-number" calculations, and how the language handles numbers that are too large or too small for its underlying representation. [REF-7] Also be careful to account for 32-bit, 64-bit, and other potential differences that may affect the numeric representation. (N/A)
Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server. (N/A)
Implementation: Examine compiler warnings closely and eliminate problems with potential security implications, such as signed / unsigned mismatch in memory operations, or use of uninitialized variables. Even if the weakness is rarely exploitable, a single failure may lead to the compromise of the entire system. (N/A)

Applicable Platforms

C (N/A, Often)
None (Not Language-Specific, Undetermined)

Demonstrative Examples

Intro: The following image processing code allocates a table for images.

Body: This code intends to allocate a table of size num_imgs, however as num_imgs grows large, the calculation determining the size of the list will eventually overflow (CWE-190). This will result in a very small list to be allocated instead. If the subsequent code operates on the list as if it were num_imgs long, it may result in many types of out-of-bounds problems (CWE-119).

img_t table_ptr; /*struct containing img data, 10kB each*/ int num_imgs; ... num_imgs = get_num_imgs(); table_ptr = (img_t*)malloc(sizeof(img_t)*num_imgs); ...

Intro: The following code excerpt from OpenSSH 3.3 demonstrates a classic case of integer overflow:

Body: If nresp has the value 1073741824 and sizeof(char*) has its typical value of 4, then the result of the operation nresp*sizeof(char*) overflows, and the argument to xmalloc() will be 0. Most malloc() implementations will happily allocate a 0-byte buffer, causing the subsequent loop iterations to overflow the heap buffer response.

nresp = packet_get_int(); if (nresp > 0) { response = xmalloc(nresp*sizeof(char*)); for (i = 0; i < nresp; i++) response[i] = packet_get_string(NULL); }

Intro: Integer overflows can be complicated and difficult to detect. The following example is an attempt to show how an integer overflow may lead to undefined looping behavior:

Body: In the above case, it is entirely possible that bytesRec may overflow, continuously creating a lower number than MAXGET and also overwriting the first MAXGET-1 bytes of buf.

short int bytesRec = 0; char buf[SOMEBIGNUM]; while(bytesRec < MAXGET) { bytesRec += getFromInput(buf+bytesRec); }

Intro: In this example the method determineFirstQuarterRevenue is used to determine the first quarter revenue for an accounting/business application. The method retrieves the monthly sales totals for the first three months of the year, calculates the first quarter sales totals from the monthly sales totals, calculates the first quarter revenue based on the first quarter sales, and finally saves the first quarter revenue results to the database.

Body: However, in this example the primitive type short int is used for both the monthly and the quarterly sales variables. In C the short int primitive type has a maximum value of 32768. This creates a potential integer overflow if the value for the three monthly sales adds up to more than the maximum value for the short int primitive type. An integer overflow can lead to data corruption, unexpected behavior, infinite loops and system crashes. To correct the situation the appropriate primitive type should be used, as in the example below, and/or provide some validation mechanism to ensure that the maximum value for the primitive type is not exceeded.

#define JAN 1 #define FEB 2 #define MAR 3 short getMonthlySales(int month) {...} float calculateRevenueForQuarter(short quarterSold) {...} int determineFirstQuarterRevenue() { // Variable for sales revenue for the quarter float quarterRevenue = 0.0f; short JanSold = getMonthlySales(JAN); /* Get sales in January */ short FebSold = getMonthlySales(FEB); /* Get sales in February */ short MarSold = getMonthlySales(MAR); /* Get sales in March */ // Calculate quarterly total short quarterSold = JanSold + FebSold + MarSold; // Calculate the total revenue for the quarter quarterRevenue = calculateRevenueForQuarter(quarterSold); saveFirstQuarterRevenue(quarterRevenue); return 0; }

Notes

Relationship: Integer overflows can be primary to buffer overflows when they cause less memory to be allocated than expected.
Terminology: "Integer overflow" is sometimes used to cover several types of errors, including signedness errors, or buffer overflows that involve manipulation of integer data types instead of characters. Part of the confusion results from the fact that 0xffffffff is -1 in a signed context. Other confusion also arises because of the role that integer overflows have in chains. A "wraparound" is a well-defined, standard behavior that follows specific rules for how to handle situations when the intended numeric value is too large or too small to be represented, as specified in standards such as C11. "Overflow" is sometimes conflated with "wraparound" but typically indicates a non-standard or undefined behavior. The "overflow" term is sometimes used to indicate cases where either the maximum or the minimum is exceeded, but others might only use "overflow" to indicate exceeding the maximum while using "underflow" for exceeding the minimum. Some people use "overflow" to mean any value outside the representable range - whether greater than the maximum, or less than the minimum - but CWE uses "underflow" for cases in which the intended result is less than the minimum. See [REF-1440] for additional explanation of the ambiguity of terminology.
Other: While there may be circumstances in which the logic intentionally relies on wrapping - such as with modular arithmetic in timers or counters - it can have security consequences if the wrap is unexpected. This is especially the case if the integer overflow can be triggered using user-supplied inputs.

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