Base64ValidationWithoutStrictMode

warning native on by default

Group: Probable bugs

Non-strict base64 decoding can discard invalid characters. Enable strict mode when the result is being used to validate an encoding.

Example

<?php
if(base64_decode($token)===false){return false;}

Reported:

• line 2: Enable strict base64 decoding when validating input.

Detection

• Resolved base64_decode with absent/false strict argument is compared strictly to false in a condition that rejects input by throw/return. Highlight call.
• Resolve builtin functions, classes, constants and methods; user-defined lookalikes are excluded. Follow only bounded local proof in one lexical scope.
• Emit one finding per violating operation, not per supporting evidence statement. When the proof is inconclusive, nothing is reported.

Exceptions (no report)

• Do not report unresolved or shadowed builtin names, unknown values, or incomplete receiver/type provenance. Unknown calls, aliases escaping, and intervening writes invalidate local proof. Similar code outside the stated detection contract is not a finding.
• Both standard suppression forms suppress this native ID.

Fix

None. Choosing a repair requires intent or additional runtime information.

PHP versions

Available throughout supported PHP 5.3–8.5 where the referenced builtin/extension is available. Respect syntax/version-specific receiver contracts; unavailable APIs are not this rule’s concern.

Configure

In custos.json:

{
  "rules": {
    "Base64ValidationWithoutStrictMode": {
      "enabled": false
    }
  }
}

Suppress

Before the statement or declaration (or the first statement of the file):

// @custos-ignore Base64ValidationWithoutStrictMode