SB20260731175 - Remote code execution in FastJson

Description

This security bulletin contains information about 1 vulnerability.

1) Input validation error (CVE-ID: CVE-2026-16723)

CWE-ID: CWE-20 - Improper input validation

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Red

The vulnerability allows a remote attacker to execute arbitrary code.

The vulnerability exists due to improper input validation in fastjson type resolution logic when parsing user-supplied JSON input. A remote attacker can send a specially crafted JSON payload to execute arbitrary code.

Exploitation requires the application to run as a Spring Boot executable fat-jar under the default configuration with AutoType disabled and SafeMode disabled.

Remediation

Install update from vendor's website.

References

• https://github.com/alibaba/fastjson2/wiki/Security-Advisory%3A-Remote-Code-Execution-in-fastjson-1.2.68%E2%80%931.2.83
• https://github.com/alibaba/fastjson/releases/tag/1.2.84
• https://fearsoff.org/research/fastjson-1-2-83-rce