Deserialization in Lxsmnsyc Seroval
CVE-2026-59940
Seroval facilitates JS value stringification, including complex structures beyond JSON.stringify capabilities. Prior to 1.5.3, seroval.fromJSON() allows attacker-controlled JSON Promise control nodes to operate on values from the general deserialization reference table without verifying genuine internal Promise resolver records, causing deserialization side effects with plugins enabled and potentially unintended server-side invocation or remote code execution when downstream frameworks register callable wrappers. This issue is fixed in version 1.5.3.
Vulnerability class: Insecure Deserialization
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Lxsmnsyc Seroval — versions < 1.5.3
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM)
Frequently asked questions
- What is CVE-2026-59940?
- CVE-2026-59940 is a critical-severity vulnerability in Lxsmnsyc Seroval, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2026-08-18.
- How severe is CVE-2026-59940?
- Critical severity. CVSS v3 base score is 9.8 out of 10.