CWE-682 Incorrect Calculation

The product performs a calculation that generates incorrect or unintended results that are later used in security-critical decisions or resource management.

• Availability: DoS: Crash, Exit, or Restart — If the incorrect calculation causes the program to move into an unexpected state, it may lead to a crash or impairment of service. • Integrity, Confidentiality, Availability: DoS: Crash, Exit, or Restart, DoS: Resource Consumption (Other), Execute Unauthorized Code or Commands — If the incorrect calculation is used in the context of resource allocation, it could lead to an out-of-bounds operation (CWE-119) leading to a crash or even arbitrary code execution. Alternatively, it may result in an integer overflow (CWE-190) and / or a resource consumption problem (CWE-400). • Access Control: Gain Privileges or Assume Identity — In the context of privilege or permissions assignment, an incorrect calculation can provide an attacker with access to sensitive resources. • Access Control: Bypass Protection Mechanism — If the incorrect calculation leads to an insufficient comparison (CWE-697), it may compromise a protection mechanism such as a validation routine and allow an attacker to bypass the security-critical code.

• [Implementation] Understand your programming language's underlying representation and how it interacts with numeric calculation. Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, "not-a-number" calculations, and how your language handles numbers that are too large or too small for its underlying representation. • [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. • [Implementation] Use the appropriate type for the desired action. For example, in C/C++, only use unsigned types for values that could never be negative, such as height, width, or other numbers related to quantity. • [Architecture and Design] Use languages, 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++). • [Architecture and Design] Use languages, 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++). • [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.

• Manual Analysis: This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. Specifically, manual static analysis is useful for evaluating the correctness of allocation calculations. This can be useful for detecting overflow conditions (CWE-190) or similar weaknesses that might have serious security impacts on the program. • Automated Static Analysis: 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.) • Fuzzing: Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.

• CVE-2026-7270: Chain: calculation expression does not use parentheses to address operator precedence (CWE-783), causing an incorrect calculation (CWE-682) leading to a buffer overflow (CWE-787). • CVE-2020-0022: Chain: mobile phone Bluetooth implementation does not include offset when calculating packet length (CWE-682), leading to out-of-bounds write (CWE-787) • CVE-2017-8932: "carry propagation" bug in cryptography implementation on x86-64 architecture adds a carry bit from a previous unrelated operation. • CVE-2010-1378: Chain: incorrect calculation (CWE-682) allows attackers to bypass certificate checks (CWE-295) • CVE-2004-1363: substitution overflow: buffer overflow using environment variables that are expanded after the length check is performed