StableLib: Prototype poisoning via `__proto__` map keys in CBOR decoding
StableLib is a stable library of useful TypeScript and JavaScript code. Prior to 2.0.4, the @stablelib/cbor CBOR map decoding path creates ordinary JavaScript objects and assigns attacker-controlled keys with bracket assignment. A map key named __proto__ invokes the inherited prototype setter instead of creating an ordinary own property, allowing the decoded object's prototype to contain attacker-controlled authorization or feature-flag values. Downstream code that trusts normal property lookup or merges the decoded object can therefore make security-sensitive decisions using inherited attacker data. This issue is fixed in version 2.0.4.
StableLib: Stack exhaustion denial of service via deeply nested CBOR arrays, maps, or tags
StableLib is a stable library of useful TypeScript and JavaScript code. Prior to 2.0.4, the @stablelib/cbor decoder recursively processes nested CBOR arrays, maps, and tags through _decodeValue() without enforcing a maximum nesting depth. A sufficiently deep structure exhausts the JavaScript call stack, causing a decoding exception and potentially terminating an uncaught request worker or process. This issue is fixed in version 2.0.4.