# CVE-2026-16723 — Alibaba Fastjson

> As of 2026-07-23, CVE-2026-16723 is a CRITICAL-severity vulnerability in Alibaba Fastjson, CVSS v3.1 9. Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-16723, most recently “Fastjson 1.x RCE (CVE-2026-16723) — Gadget-Free Deserialization Bypass Actively Exploited in Spring Boot Fat-JAR Deployments”.

**Last updated:** 2026-07-23

## What is CVE-2026-16723?

A remote code execution (RCE) vulnerability exists in fastjson 1.2.68 through 1.2.83. This vulnerability is exploitable under fastjson's stock default configuration — no AutoType enablement required, no classpath gadget required.

The record classifies CVE-2026-16723 under weakness classes [CWE-20](https://intel.threadlinqs.com/cwe/CWE-20), [CWE-502](https://intel.threadlinqs.com/cwe/CWE-502). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 74 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 9 — CRITICAL (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H`)
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 6.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-07-23

## Is CVE-2026-16723 being exploited?

Weaponised exploit code for CVE-2026-16723 is publicly available. 10 public proof-of-concept repositories are tracked for this identifier.

- [dinosn/fastjson-jsontype-rce-lab](https://github.com/dinosn/fastjson-jsontype-rce-lab) (github)
- [learner330/fastjson-cve-2026-16723](https://github.com/learner330/fastjson-cve-2026-16723) (github)
- [why-success/fastjson-rce-lab](https://github.com/why-success/fastjson-rce-lab) (github)
- [1xPwn/CVE-2026-16723](https://github.com/1xPwn/CVE-2026-16723) (github)
- [HORKimhab/CVE-2026-16723](https://github.com/HORKimhab/CVE-2026-16723) (github)
- [EQSTLab/CVE-2026-16723](https://github.com/EQSTLab/CVE-2026-16723) (github)
- [fazilbaig1/CVE-2026-16723](https://github.com/fazilbaig1/CVE-2026-16723) (github)
- [Superman-L/CVE-2026-16723](https://github.com/Superman-L/CVE-2026-16723) (github)

## Affected products and versions

- **Alibaba**: Fastjson

Affected software packages:

- `maven:com.alibaba:fastjson`

## How to fix CVE-2026-16723

No vendor patch reference has been recorded for CVE-2026-16723 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-16723

1 tracked threat in the Threadlinqs corpus references CVE-2026-16723, either in the campaign’s CVE list or as an indicator on the campaign record.

- [Fastjson 1.x RCE (CVE-2026-16723) — Gadget-Free Deserialization Bypass Actively Exploited in Spring Boot Fat-JAR Deployments](https://intel.threadlinqs.com/threat/TL-2026-1682) — CRITICAL · 2026-07-25

## Sources

Enriched from CVE.org, NVD, GitHub Security Advisories, public proof-of-concept repositories. Last verified by Threadlinqs on 2026-09-29. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [github.com — vendor advisory](https://github.com/alibaba/fastjson2/wiki/Security-Advisory:-Remote-Code-Execution-in-fastjson-1.2.68%E2%80%931.2.83)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-16723
Full detection coverage and IOCs for threats exploiting CVE-2026-16723 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp