Raw vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-23737 is a high-severity Deserialization of Untrusted Data (CWE-502) vulnerability in Lxsmnsyc Seroval. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 47th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
Seroval is a JavaScript library designed for stringifying JavaScript values, including complex structures beyond the capabilities of JSON.stringify. CVE-2026-23737 affects versions 1.4.0 and below, stemming from improper input handling in the JSON deserialization component, which can lead to arbitrary JavaScript code execution. The vulnerability specifically impacts the fromJSON and fromCrossJSON functions in client-to-server transmission scenarios, classified under CWE-502 (Deserialization of Untrusted Data) with a CVSS v3.1 base score of 7.5 (AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H).
Exploitation requires attackers to have low privileges (PR:L) and network access (AV:N), but demands high attack complexity (AC:H) with no user interaction needed. At minimum, attackers must perform four separate requests targeting the same function and possess partial knowledge of how the serialized data is processed at runtime. This enables overriding constant values and error deserialization, providing indirect access to unsafe JavaScript evaluation and resulting in high impacts to confidentiality, integrity, and availability.
The issue has been fixed in seroval version 1.4.0. Mitigation involves upgrading to this patched version. Additional details are available in the GitHub security advisory (GHSA-3rxj-6cgf-8cfw) and the associated commit (ce9408ebc87312fcad345a73c172212f2a798060).
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-3679
Vulnerability Data
seroval facilitates JS value stringification, including complex structures beyond JSON.stringify capabilities. In versions 1.4.0 and below, improper input handling in the JSON deserialization component can lead to arbitrary JavaScript code execution. Exploitation is possible via overriding constant value and error…
more
deserialization, allowing indirect access to unsafe JS evaluation. At minimum, attackers need 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 fromCrossJSON functions in a client-to-server transmission scenario. This issue has been fixed in version 1.4.0.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation can uncover deserialization flaws before deployment.
Input validation directly stops deserialization of untrusted data by ensuring inputs are valid before processing.
Engineering principles such as safe deserialization and input sanitization structurally prevent the weakness from being introduced.
Integrity verification tools can detect malformed or tampered serialized data after the fact.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing includes validation of deserialization routines and the use of untrusted data, reducing the likelihood that unsafe object reconstruction will be deployed.
Requiring vetted libraries, regular updates and SAST before release reduces the likelihood that deserialization logic will accept and act on attacker-controlled serialized objects.
Regular scanning of third-party libraries and timely patching reduce the likelihood that unsafe deserialization vulnerabilities remain active.