Detections
Analytics

FastJSON Object Deserialization

critical Web App Scanning Plugin ID 114884

Synopsis

FastJSON Object Deserialization

Description

Serialization is the process of converting an object to a stream of bytes, in order to store or send it through the network. By opposition, deserialization is the process of reconstructing an object from this stream of bytes.

When an application using the FastJSON library performs untrusted data deserialization, an attacker could inject a custom serialized JSON object to trigger malicious code execution on the system or to generate a Denial of Service attack (DoS).

It was determined that the target Java application using FastJSON is vulnerable to this attack as it deserializes a user-supplied object.

Solution

Untrusted data should never be deserialized by the application. If required, a code review should be done to prevent deserialization of arbitrary classes and to harden the whole process. Ensure the FastJSON library is updated to the latest version, and consider using FastJSON's safe mode or implementing custom whitelisting/blacklisting of classes for deserialization if updating is not immediately possible.

See Also

https://cheatsheetseries.owasp.org/cheatsheets/Deserialization_Cheat_Sheet.html

https://github.com/alibaba/fastjson

https://resources.infosecinstitute.com/10-steps-avoid-insecure-deserialization/#gref

https://www.owasp.org/index.php/Deserialization_of_untrusted_data

Plugin Details

Severity: Critical

ID: 114884

Type: remote

Published: 6/17/2025

Updated: 6/17/2025

Scan Template: api, pci, scan

Risk Information

CVSS v2

Risk Factor: High

Base Score: 7.6

Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:C

CVSS Score Source: Tenable

CVSS v3

Risk Factor: Critical

Base Score: 9

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS Score Source: Tenable

CVSS v4

Risk Factor: Critical

Base Score: 9.2

Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS Score Source: Tenable

Vulnerability Information

Exploit Available: true

Reference Information