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VulnerabilityPublished Updated

CVE-2026-27206: zumba json-serializer · Deserialization of Untrusted Data

Affects zumba json-serializerSource CVE Database V5

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Not known to be exploited · CVSS 8.1 High : upgrade to 3.2.3 soon.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score
8.1High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.8% chance of exploitation in 30 days – higher than 57% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 3.2.3
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 21 Feb 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade zumba json-serializer to 3.2.3.

Affected software

ProductAffectedFixed in
zumbajson-serializerAffected
  • <3.2.3
Fixed in
  • 3.2.3

AI-suggested

  1. Upgrade the zumba json-serializer library to version 3.2.3 or later immediately to apply the official fix that restricts unsafe @type-based deserialization.
  2. Audit all application code to identify any usage of JsonSerializer::unserialize() and ensure it is never called with untrusted or attacker-controlled JSON input.
  3. Implement strict input validation and sanitization on all JSON data before deserialization to prevent injection of malicious @type fields.
  4. Where possible, disable or remove support for the @type field in the deserializer configuration to prevent arbitrary class instantiation.
  5. Conduct a review of all classes available in the application and dependencies to identify and harden or remove classes with dangerous magic methods that could be used as gadget chains.
  6. Employ runtime application self-protection (RASP) or web application firewalls (WAF) with rules to detect and block suspicious JSON payloads containing @type fields or unusual object instantiation patterns.
  7. Monitor application logs for unusual deserialization activity or errors that may indicate exploitation attempts.
  8. Educate developers about the risks of unsafe deserialization and enforce secure coding practices around object deserialization in PHP.

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.

References

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