Integer Overflow in Adonisjs with Api Keys

AdonisJS applications that manage API keys via numeric identifiers or usage counters can be exposed to integer overflow when values exceed the safe integer range of JavaScript (Number.MAX_SAFE_INTEGER, 2^53 - 1) or the underlying storage type. In AdonisJS, API keys are often represented as BigInts or strings in models, but intermediate calculations—such as incrementing a usage counter, computing a rolling quota window, or deriving a numeric segment for partitioning—may temporarily use JavaScript Number types. If user-supplied or derived values are not validated and coerced safely, arithmetic like counter + 1 or end - start can wrap around, leading to unexpected behavior, privilege escalation, or bypass of rate limits.

Consider an endpoint that increments a usage counter stored as a JavaScript Number before saving to the database:

import ApiKey from 'App/Models/ApiKey'

async function incrementUsage(keyId: number) {
  const key = await ApiKey.find(keyId)
  if (!key) {
    throw new Error('Not found')
  }
  // Risk: key.usage is a Number; large values can overflow
  key.usage = key.usage + 1
  await key.save()
  return key
}

If key.usage approaches or exceeds 2^53, the increment can wrap to a negative number or a very small integer. An attacker who can cause repeated increments—potentially via a compromised or guessed API key—might force the counter to wrap to zero, effectively resetting quota restrictions or bypassing rate limiting. Similarly, computing time windows using subtraction can underflow, producing large positive numbers that incorrectly validate as within a window.

AdonisJS middleware that validates API keys often parses identifiers or timestamps as Numbers. If an API key encodes a numeric timestamp or shard index, and the application performs arithmetic to derive access permissions, overflow can map a key to an unintended shard or time bucket. This can enable horizontal privilege escalation across API key segments (BOLA/IDOR) or bypass property-level authorization checks tied to computed attributes.

The risk is compounded when OpenAPI specs define numeric formats without constraining ranges. middleBrick’s 12 security checks run in parallel and include Property Authorization and Input Validation, which can flag unsafe arithmetic patterns. Its LLM/AI Security probes do not test integer overflow directly, but the scanner’s runtime checks can surface anomalous behavior consistent with overflow-induced logic flaws, contributing to a higher risk score and findings mapped to OWASP API Top 10 and CWE-190.

Remediation centers on avoiding unsafe JavaScript Number arithmetic for values that can grow large or be attacker-influenced. Use BigInt for counters and timestamps, validate ranges explicitly, and ensure serialization/deserialization preserves type integrity. Below are concrete patterns and code examples tailored to API key handling in AdonisJS.

1. Use BigInt for usage counters and quotas

Store and increment usage as BigInt to avoid overflow. Ensure your database column type supports large integers (e.g., BIGINT in SQL) and treat values as BigInt in JavaScript:

import ApiKey from 'App/Models/ApiKey'

async function safeIncrementUsage(keyId: number) {
  const key = await ApiKey.find(keyId)
  if (!key) {
    throw new Error('Not found')
  }
  // Use BigInt to prevent overflow
  const current = BigInt(key.usage)
  key.usage = current + 1n
  await key.save()
  return key
}

2. Validate numeric input ranges before arithmetic

When accepting numeric parameters derived from API keys or timestamps, clamp or reject values outside a safe range before performing arithmetic:

function clampToSafeInteger(value: number): number {
  const safeMax = Number.MAX_SAFE_INTEGER
  const safeMin = Number.MIN_SAFE_INTEGER
  if (value > safeMax || value < safeMin) {
    throw new Error('Value out of safe integer range')
  }
  return value
}

async function computeWindow(startInput: number, endInput: number) {
  const start = clampToSafeInteger(startInput)
  const end = clampToSafeInteger(endInput)
  if (end - start < 0) {
    throw new Error('Invalid window')
  }
  // Proceed with safe calculation
  return end - start
}

3. Use string-based identifiers and constant-time comparison

Treat API keys as opaque strings and avoid embedding numeric semantics that encourage parsing. When comparisons are needed, use constant-time helpers to avoid timing side channels:

import { compare } from 'fast-safe-stringify'

async function verifyKey(inputKey: string, storedKey: string) {
  // Constant-time comparison to avoid leaking via timing
  return compare(inputKey, storedKey)
}

4. Enforce schema constraints in models and serializers

Define explicit ranges in your AdonisJS schema or Lucid model validations to reject values that could overflow downstream calculations:

import { schema } from '@ioc:Adonis/Core/Validator'

const apiKeySchema = schema.create({
  usage: schema.number.unsigned().max(2 ** 53 - 1), // enforce safe integer bound
  quotaLimit: schema.number.unsigned().max(1_000_000)
})

export const validateApiKey = (payload) => {
  const validated = apiKeySchema.validate(payload)
  return validated
}

By combining BigInt usage, strict range validation, opaque key handling, and runtime checks, you mitigate integer overflow risks specific to API key management in AdonisJS.