seroval writes a RegExp as a regular expression literal. In affected versions, the < character in a RegExp source is written without escaping. A source built from untrusted input can then end the HTML <script> element that the serialized output is placed in, and run script in the page.
fromJSON and fromCrossJSON used two node fields without checking them. An array node's element list was not checked to be an array. A small payload could set the length the decoder looped over. This part is also tracked in GHSA-wp97-x4hv-qvhp. A sequence node's done index was not checked. A crafted value produced an iterator that never finished.
When fromJSON rebuilt an async iterator, it called on() on the iterator's source without checking that the source was a seroval stream. A crafted payload could pick another value as the source, such as a function returned by an application plugin. The deserializer then called that value's on method. This is a variant of GHSA-mv8w-475r-vwqw. That fix covered the promise and stream control nodes but not the async iterator node.
seroval writes a typed array as a call to its constructor. In affected versions, the constructor name in the output is read from a property that data on the value can replace, and it is written without checks. A typed array that received properties from untrusted data can then put arbitrary code into the serialized output.
fromJSON and fromCrossJSON did not check that an array node's element list is an array. A small crafted payload could set the length the decoder used. That length controlled how much memory was allocated and how many times the decoder looped, and it did not depend on the size of the payload.
deserializeTypedArray casts the source node to ArrayBuffer without checking it and never bounds the element count. Pass a plain object with a length property and it hits the array-like TypedArray constructor, allocating that many elements. The offset guard above it can't stop this: source.byteLength is undefined, so the comparison is always false. The length is one integer in the JSON, so a tiny payload can name any allocation size, and …
A fulfilled Promise node deserialized by fromJSON() can trigger unintended invocation of a plugin-produced callable through native ECMAScript thenable assimilation. This bypasses the type-confusion fix in seroval@1.5.3 (GHSA-mv8w-475r-vwqw / CVE-2026-59940) and affects every plugin-capable release from 0.12.0 through the current 1.6.0.
A type confusion issue in seroval.fromJSON() allowed attacker-controlled JSON input to cause Promise control nodes to operate on values from the general deserialization reference table without first verifying that those values were genuine internal promise resolver records. In applications that deserialize untrusted Seroval JSON with plugins enabled, this could allow attacker-controlled deserialization side effects. In downstream server frameworks that register plugins returning callable wrappers, this primitive could become unintended server-side …
Serialization of objects with extreme depth can exceed the maximum call stack limit. Mitigation: Seroval introduces a depthLimit parameter in serialization/deserialization methods. An error will be thrown if the depth limit is reached.
Improper input handling in the JSON deserialization component can lead to arbitrary JavaScript code execution. The vulnerability can be exploited via overriding constant value and error deserialization, which allows indirect access to unsafe JS evaluation. This requires at least the ability to perform 4 separate requests on the same function and partial knowledge of how the serialized data is used during later runtime processing. This vulnerability affects the fromJSON and …
Due to improper input validation, a malicious object key can lead to prototype pollution during JSON deserialization. This affects only JSON deserialization functionality. As there is no known workaround, please upgrade to the latest version.
Overriding RegExp serialization with extremely large patterns can exhaust JavaScript runtime memory during deserialization. Additionally, overriding RegExp serialization with patterns that trigger catastrophic backtracking can lead to ReDoS (Regular Expression Denial of Service). Mitigation: Seroval introduces disabledFeatures (a bitmask) in serialization/deserialization methods, with Feature.RegExp as a dedicated flag. Users are recommended to configure disabledFeatures to disable RegExp serialization entirely.
Overriding encoded array lengths by replacing them with an excessively large value causes the deserialization process to significantly increase processing time. Mitigation: Seroval no longer encodes array lengths. Instead, it computes length using Array.prototype.length during deserialization.