CVE-2026-59940 CRITICAL

CVE-2026-59940: Seroval: `seroval.fromJSON()` Promise resolver type confusion invokes attacker-controlled methods during deserialization

Vendor Lxsmnsyc
Product seroval
Weakness CWE-502 · Unsafe deserialization
Published August 18, 2026
Last update August 18, 2026

CVSS base score

9.8/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

August 18, 2026 CVE published
August 18, 2026 Record updated