CVE-2026-116581 in Seroval
Summary
by MITRE • 10/26/2026
Seroval facilitates JavaScript value stringification, including complex structures beyond JSON.stringify capabilities. Prior to 1.6.8, fromJSON and fromCrossJSON do not validate a sequence node's done index. A crafted done index can create an iterator that never finishes when application code consumes it to completion. An unauthenticated request to a service that deserializes untrusted input can therefore block the event loop, exhaust process memory, or make the service unavailable. This issue is fixed in version 1.6.8.
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Analysis
by VulDB Data Team • 10/27/2026
The vulnerability identified in Seroval versions prior to 1.6.8 represents a critical flaw in the deserialization logic that handles JavaScript value stringification and reconstruction. Seroval is designed to facilitate the serialization of complex JavaScript structures, including those with circular references or other complexities that exceed the capabilities of standard JSON.stringify methods. While this functionality provides significant utility for developers needing robust data interchange formats, it introduces a substantial attack surface when processing untrusted input. The core issue lies within the fromJSON and fromCrossJSON functions, which are responsible for reconstructing JavaScript objects from serialized string representations. These functions failed to properly validate the done index associated with sequence nodes during the parsing process. This lack of validation allows an attacker to craft a maliciously constructed payload that manipulates the internal state of the iterator used to traverse the deserialized data structure.
From a technical perspective, the flaw enables the creation of an infinite loop within the deserialization routine. When application code consumes this crafted input to completion, the malformed done index prevents the iteration from terminating as expected. This behavior directly leads to a denial-of-service condition by blocking the event loop in Node.js environments or exhausting process memory resources. In single-threaded execution models common in JavaScript runtimes, such an infinite loop effectively freezes the application, rendering it unresponsive to legitimate requests. The impact is severe for any service that accepts and deserializes user-supplied data without adequate sanitization or validation layers prior to invoking Seroval's parsing functions. An unauthenticated attacker can exploit this by sending a specifically crafted HTTP request containing the malicious serialized payload, thereby causing immediate service degradation or complete outage depending on the resource constraints of the host system.
This vulnerability aligns with CWE-400, which describes Uncontrolled Resource Consumption, as well as CWE-787, Out-of-bounds Write, insofar as it involves improper validation leading to unstable state execution. In terms of the MITRE ATT&CK framework, this exploit maps to T1496, Resource Hijacking, where an adversary uses computing resources for their own purposes rather than those intended by the system owner. The attack vector is primarily network-based if the vulnerable service exposes its deserialization endpoint publicly, classifying it as a remote code execution variant that results in denial of service rather than arbitrary command execution. However, given the nature of JavaScript engines and potential prototype pollution risks inherent in complex object manipulation, there may be secondary implications for integrity violations if the malformed state allows for unexpected property injection before the loop hangs.
Mitigation strategies must focus on both immediate patching and architectural hardening. The primary remediation is to upgrade Seroval to version 1.6.8 or later, where this validation logic has been corrected to ensure that sequence node done indices are properly checked against expected bounds. Beyond updating dependencies, developers should implement strict input validation policies for all data entering deserialization functions. This includes whitelisting allowed types and structures rather than relying on blacklisting known bad inputs. Additionally, implementing timeout mechanisms or resource limits at the application level can provide a secondary layer of defense by terminating long-running operations that exceed expected execution times. It is also advisable to isolate services that handle untrusted data in sandboxed environments with restricted memory access to limit the blast radius of such attacks. Regular security audits and static code analysis tools configured to detect unsafe deserialization patterns should be integrated into the development lifecycle to prevent similar vulnerabilities from being introduced in future updates.