Deserialization in Lxsmnsyc Seroval

CVE-2026-23737

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 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.

Vulnerability class: Insecure Deserialization

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.006 (46.2th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 46.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-23737: held from 0.005 to 0.006.

EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.001

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-23737?
CVE-2026-23737 is a high-severity vulnerability in Lxsmnsyc Seroval, classified under Deserialization of Untrusted Data. CVSS score: 7.5/10. Published 2026-01-21.
How severe is CVE-2026-23737?
High severity. CVSS v3 base score is 7.5 out of 10.