Fluent Forms – Customizable Contact Forms, Survey, Quiz, & Conversational Form Builder 5.1.16 - 6.1.1 - Authenticated (Subscriber+) PHP Object Injection To Arbitrary File Read

Deserialization of Untrusted Data
CVE CVE-2025-9260
CVSS Medium (6.5)
Publicly Published September 2, 2025
Last Updated September 5, 2025
Researcher Webbernaut
Description

The Fluent Forms – Customizable Contact Forms, Survey, Quiz, & Conversational Form Builder plugin for WordPress is vulnerable to PHP Object Injection in versions 5.1.16 to 6.1.1 via deserialization of untrusted input in the parseUserProperties function. This makes it possible for authenticated attackers, with Subscriber-level access and above, to inject a PHP Object. The additional presence of a POP chain allows attackers to read arbitrary files. If allow_url_include is enabled on the server, remote code execution is possible. While the vendor patched this issue in version 6.1.0, the patch caused a fatal error in the vulnerable code, due to a missing class import, so we consider 6.1.2 to be the most complete and best patched version.

References

1 affected software package

Software Type Plugin
Software Slug fluentform (view on wordpress.org)
Patched? Yes
Affected Version
  • 5.1.16 - 6.1.1
Patched Version
  • 6.1.2
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