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Security Advisories: GSA_kwCzR0hTQS04Mmp2LTl3anctcHFoNs4AA7KU

Prototype pollution in emit function

Summary

A prototype pollution in derby can crash the application, if the application author has atypical HTML templates that feed user input into an object key.

Attribute keys are almost always developer-controlled, not end-user-controlled, so this shouldn't be an issue in practice for most applications.

Details

emit(context: Context, target: T) {
  const node = traverseAndCreate(context.controller, this.segments);
    node[this.lastSegment] = target;
    this.addListeners(target, node, this.lastSegment);
}

The emit() function in src/templates/templates.ts is called without sanitizing the variable this.lastSegment . The variable this.lastSegment can be set to __proto__, and this will pollute the prototype of Javascipt Object (node['__proto__'] = target).

PoC

To reproduce this vulnerability, you can adjust the test case ignores DOM mutations in components\' create() in test/dom/ComponentHarness.mocha.js.

it('ignores DOM mutations in components\' create()', function() {
      function Box() {}
      Box.view = {
        is: 'box',
-        source: '<index:><div class="box" as="boxElement"></div>'
+        source: '<index:><div class="box" as="__proto__"></div>'
      };
      Box.prototype.create = function() {
        this.boxElement.className = 'box-changed-in-create';
      };
      var harness = runner.createHarness('<view is="box" />', Box);
      expect(harness).to.render('<div class="box"></div>');
});

When as attribute is controlled by attackers, the variable in this.lastSegment will exactly take value __proto__ and prototype pollution happens.

Patch

Add a check on this.lastSegment can prevent this attack.

emit(context: Context, target: T) {
  const node = traverseAndCreate(context.controller, this.segments);
+  if (this.lastSegment.includes('__proto__') || this.lastSegment.includes('prototype')) {
+    throw new Error('Unsafe code detected');
+  }
    node[this.lastSegment] = target;
    this.addListeners(target, node, this.lastSegment);
}
Permalink: https://github.com/advisories/GHSA-82jv-9wjw-pqh6
JSON: https://advisories.ecosyste.ms/api/v1/advisories/GSA_kwCzR0hTQS04Mmp2LTl3anctcHFoNs4AA7KU
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Low
Classification: General
Published: about 1 month ago
Updated: about 1 month ago


Identifiers: GHSA-82jv-9wjw-pqh6
References: Repository: https://github.com/derbyjs/derby
Blast Radius: 0.0

Affected Packages

npm:derby
Dependent packages: 29
Dependent repositories: 252
Downloads: 2,986 last month
Affected Version Ranges: >= 4.0.0-beta1, <= 4.0.0-beta.10, >= 3.0.0, <= 3.0.1, <= 2.3.1
Fixed in: 4.0.0-beta.11, 3.0.2, 2.3.2
All affected versions: 0.0.1, 0.0.2, 0.0.3, 0.0.4, 0.0.5, 0.0.6, 0.0.7, 0.0.8, 0.0.9, 0.0.10, 0.1.0, 0.1.1, 0.1.2, 0.1.3, 0.1.4, 0.1.5, 0.1.6, 0.1.7, 0.1.8, 0.1.9, 0.1.10, 0.3.0, 0.3.1, 0.3.2, 0.3.3, 0.3.4, 0.3.5, 0.3.6, 0.3.7, 0.3.8, 0.3.9, 0.3.10, 0.3.11, 0.3.12, 0.3.13, 0.3.14, 0.3.15, 0.3.16, 0.3.17, 0.3.18, 0.3.19, 0.5.0, 0.5.1, 0.5.2, 0.5.3, 0.5.4, 0.5.5, 0.5.6, 0.5.7, 0.5.9, 0.5.10, 0.5.11, 0.5.12, 0.5.16, 0.7.1, 0.8.0, 0.8.1, 0.8.2, 0.8.3, 0.8.4, 0.8.5, 0.9.0, 0.9.1, 0.9.2, 0.9.3, 0.9.4, 0.9.5, 0.9.6, 0.9.7, 0.10.0, 0.10.1, 0.10.2, 0.10.3, 0.10.4, 0.10.5, 0.10.8, 0.10.9, 0.10.10, 0.10.11, 0.10.12, 0.10.13, 0.10.14, 0.10.15, 0.10.16, 0.10.17, 0.10.18, 0.10.19, 0.10.20, 0.10.21, 0.10.22, 0.10.23, 0.10.24, 0.10.25, 0.10.26, 0.10.27, 0.10.28, 0.10.29, 0.10.30, 0.10.31, 1.0.0, 1.0.1, 1.1.0, 2.0.0, 2.0.1, 2.0.2, 2.0.3, 2.1.0, 2.2.0, 2.3.0, 2.3.1, 3.0.0, 3.0.1
All unaffected versions: 2.3.2, 2.3.3, 3.0.2, 3.0.3, 4.0.0, 4.1.0, 4.1.1, 4.1.2