GHSA-fqg8-vfv7-8fj8

### Impact

In JSONata versions `>= 1.4.0, < 1.8.7` and `>= 2.0.0, < 2.0.4`, a malicious expression can use the [transform operator](https://docs.jsonata.org/other-operators#-------transform) to override properties on the `Object` constructor and prototype. This may lead to denial of service, remote code execution or other unexpected behavior in applications that evaluate user-provided JSONata expressions.

### Patch

This issue has been fixed in JSONata versions `>= 1.8.7` and `>= 2.0.4`. Applications that evaluate user-provided expressions should update ASAP to prevent exploitation. The following patch can be applied if updating is not possible.

```patch --- a/src/jsonata.js +++ b/src/jsonata.js @@ -1293,6 +1293,13 @@ var jsonata = (function() { } for(var ii = 0; ii < matches.length; ii++) { var match = matches[ii]; + if (match && (match.isPrototypeOf(result) || match instanceof Object.constructor)) { + throw { + code: "D1010", + stack: (new Error()).stack, + position: expr.position + }; + } // evaluate the update value for each match var update = await evaluate(expr.update, match, environment); // update must be an object @@ -1539,7 +1546,7 @@ var jsonata = (function() { if (typeof err.token == 'undefined' && typeof proc.token !== 'undefined') { err.token = proc.token; } - err.position = proc.position; + err.position = proc.position || err.position; } throw err; } @@ -1972,6 +1979,7 @@ var jsonata = (function() { "T1007": "Attempted to partially apply a non-function. Did you mean ${{{token}}}?", "T1008": "Attempted to partially apply a non-function", "D1009": "Multiple key definitions evaluate to same key: {{value}}", + "D1010": "Attempted to access the Javascript object prototype", // Javascript specific "T1010": "The matcher function argument passed to function {{token}} does not return the correct object structure", "T2001": "The left side of the {{token}} operator must evaluate to a number", "T2002": "The right side of the {{token}} operator must evaluate to a number", ```

### References

https://github.com/jsonata-js/jsonata/releases/tag/v2.0.4

### Credit

Thank you to Albert Pedersen of Cloudflare for disclosing this issue.