vulnerability / NVI-00014078 / Revision 1
Tiptap: mergeAttributes() turns an own __proto__ key into inherited executable DOM attributes
GitHub lists this reviewed advisory for @tiptap/core. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
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02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
@tiptap/core
source listed>= 2.0.0-alpha.0, < 3.30.4
## Summary `@tiptap/core`'s public `mergeAttributes()` helper uses ordinary bracket assignment on keys returned by `Object.entries()`. An own `__proto__` key from JSON therefore invokes the legacy prototype setter on the fresh merged object. The function returns an object whose prototype is attacker-controlled, while `Object.keys()` and ordinary own-property checks show no attacker attributes. When that result is used as a ProseMirror DOMOutputSpec attribute object, `prosemirror-model`'s `DOMSerializer.renderSpec()` enumerates it with `for...in` and applies inherited values with `setAttribute()`. In a browser proof, inherited `src` and `onerror` values were copied to an `` and the error handler executed once. This is per-object prototype manipulation; the proof does not modify global `Object.prototype`. ## Root cause The affected loop is conceptually: ```ts const mergedAttributes = { ...items } for (const [key, value] of Object.entries(item)) { const exists = mergedAttributes[key] // ... mergedAttributes[key] = value } ``` `Object.entries(JSON.parse('{"__proto__": {...}}'))` includes `__proto__`. Reading `mergedAttributes['__proto__']` resolves the inherited `Objec
03 / Response
What to do next
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04 / Limits
What this report cannot establish
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05 / Provenance
Sources you can inspect
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- GHSA-cp6q-959q-f8rh ↗
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- Revision 1 ·
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