CVE-2026-23736 in seroval
Summary
by MITRE • 01/22/2026
seroval facilitates JS value stringification, including complex structures beyond JSON.stringify capabilities. In versions 1.4.0 and below, due to improper input validation, a malicious object key can lead to prototype pollution during JSON deserialization. This vulnerability affects only JSON deserialization functionality. This issue is fixed in version 1.4.1.
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Analysis
by VulDB Data Team • 02/27/2026
The vulnerability identified as CVE-2026-23736 resides within the seroval library, a tool designed to facilitate JavaScript value stringification beyond the capabilities of standard JSON.stringify methods. This library serves as a utility for converting complex JavaScript data structures into serializable formats, making it an essential component in applications that require robust data handling and transmission capabilities. The flaw specifically manifests during JSON deserialization processes where the library fails to properly validate input parameters, creating a pathway for malicious actors to exploit prototype pollution vulnerabilities.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within seroval's deserialization logic. When processing JSON data containing specially crafted object keys, the library does not sufficiently sanitize or validate the structure of incoming data, allowing attackers to manipulate prototype properties during the deserialization process. This prototype pollution occurs because the library treats user-provided keys as legitimate property names without proper validation, enabling malicious actors to inject or modify properties on the Object prototype. The vulnerability is particularly concerning as it operates at the core of data parsing functionality, affecting how applications handle serialized JavaScript objects and potentially allowing attackers to execute arbitrary code or manipulate application behavior.
The operational impact of this vulnerability extends beyond simple data corruption, as prototype pollution can lead to severe security consequences including privilege escalation, denial of service attacks, and potential remote code execution in vulnerable applications. When exploited, this vulnerability allows attackers to modify the behavior of fundamental JavaScript objects and their prototypes, which can subsequently affect application logic, authentication mechanisms, or data validation processes. The impact is amplified in environments where seroval is used for processing untrusted input from external sources, such as API endpoints, user uploads, or third-party integrations. Security researchers have classified this issue as particularly dangerous due to its ability to affect core JavaScript object behavior and its potential for cascading effects throughout application codebases that rely on standard object prototypes.
Mitigation strategies for CVE-2026-23736 focus primarily on updating to the patched version 1.4.1 of the seroval library, which implements proper input validation and sanitization measures to prevent prototype pollution during JSON deserialization. Organizations should conduct comprehensive vulnerability assessments to identify all applications and systems that utilize seroval, particularly those handling external data inputs. The fix addresses the root cause by implementing strict validation of object keys and ensuring that deserialization processes do not inadvertently modify prototype properties. Security teams should also consider implementing additional defensive measures such as input sanitization at multiple layers, monitoring for unusual prototype modifications, and conducting regular security audits of third-party dependencies. This vulnerability aligns with CWE-471, which addresses the weakness of using an incorrect function in a context where a different function is expected, and relates to ATT&CK technique T1190, which involves exploiting vulnerabilities in applications to gain unauthorized access or execute malicious code. Organizations should also review their dependency management practices to ensure timely patching of similar vulnerabilities across their software supply chain.