CVE-2026-59940: Lxsmnsyc Seroval

Critical severity, CVSS 9.8. EPSS: 0.8% chance of exploitation in the next 30 days.

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.

Affected products

• Lxsmnsyc Seroval: before 1.5.3 (fixed in 1.5.3)

Published 2026-08-18. Last modified 2026-09-18.