CWE-682 Pillar Draft High likelihood

Incorrect Calculation

This vulnerability occurs when software performs a calculation that produces wrong or unexpected results, which are then used to make security decisions or manage critical resources.

Definition

What is CWE-682?

This vulnerability occurs when software performs a calculation that produces wrong or unexpected results, which are then used to make security decisions or manage critical resources.

Incorrect calculations can directly lead to serious security flaws, such as misallocating memory, granting incorrect permissions, or failing authentication checks. These errors often stem from issues like integer overflows, off-by-one mistakes, or incorrect type conversions during critical operations. When these flawed results feed into security mechanisms, the consequences can escalate significantly. A simple math error might disable a protection feature, allow unauthorized access, or in severe cases, create conditions that enable remote code execution or complete system compromise.

Real-world impact

Real-world CVEs caused by CWE-682

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-2004-1363

substitution overflow: buffer overflow using environment variables that are expanded after the length check is performed

How attackers exploit it

Step-by-step attacker path

1
The following image processing code allocates a table for images.
2
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).
3
This code attempts to calculate a football team's average number of yards gained per touchdown.
4
The code does not consider the event that the team they are querying has not scored a touchdown, but has gained yardage. In that case, we should expect an ArithmeticException to be thrown by the JVM. This could lead to a loss of availability if our error handling code is not set up correctly.
5
This example attempts to calculate the position of the second byte of a pointer.

Vulnerable code example

Vulnerable C

The following image processing code allocates a table for images.

Vulnerable C

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);
  ...

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-682

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.
Testing Use automated static analysis tools that target this type of weakness. Many modern techniques use data flow analysis to minimize the number of false positives. This is not a perfect solution, since 100% accuracy and coverage are not feasible.
Testing Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

Detection signals

How to detect CWE-682

Manual Analysis High

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.

Plexicus auto-fix

Plexicus auto-detects CWE-682 and opens a fix PR in under 60 seconds.

Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.

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Frequently asked questions

What is CWE-682?

This vulnerability occurs when software performs a calculation that produces wrong or unexpected results, which are then used to make security decisions or manage critical resources.

How serious is CWE-682?

MITRE rates the likelihood of exploit as High — this weakness is actively exploited in the wild and should be prioritized for remediation.

What languages or platforms are affected by CWE-682?

MITRE lists the following affected platforms: Not Technology-Specific.

How can I prevent CWE-682?

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. Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the…

How does Plexicus detect and fix CWE-682?

Plexicus's SAST engine matches the data-flow signature for CWE-682 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-682?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/682.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-682

CWE-170 Can precede

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Incorrect Calculation

What is CWE-682?

Real-world CVEs caused by CWE-682

Step-by-step attacker path

Vulnerable C

Secure pseudo

How to prevent CWE-682

How to detect CWE-682

Plexicus auto-detects CWE-682 and opens a fix PR in under 60 seconds.

Frequently asked questions

Weaknesses related to CWE-682

Improper Null Termination

Wrap-around Error