CVE Vulnerabilities


Deserialization of Untrusted Data

Published: Aug 30, 2021 | Modified: Sep 02, 2021
CVSS 3.x
CVSS 2.x

The bt_bb_get_grid AJAX action of the Bold Page Builder WordPress plugin before 3.1.6 passes user input into the unserialize() function without any validation or sanitisation, which could lead to a PHP Object Injection. Even though the plugin did not contain a suitable gadget to fully exploit the issue, other installed plugins on the blog could allow such issue to be exploited and lead to RCE in some cases.


The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.

Affected Software

Name Vendor Start Version End Version
Bold_page_builder Bold-themes * 3.1.6 (excluding)

Extended Description

It is often convenient to serialize objects for communication or to save them for later use. However, deserialized data or code can often be modified without using the provided accessor functions if it does not use cryptography to protect itself. Furthermore, any cryptography would still be client-side security – which is a dangerous security assumption. Data that is untrusted can not be trusted to be well-formed. When developers place no restrictions on “gadget chains,” or series of instances and method invocations that can self-execute during the deserialization process (i.e., before the object is returned to the caller), it is sometimes possible for attackers to leverage them to perform unauthorized actions, like generating a shell.

Potential Mitigations

  • Make fields transient to protect them from deserialization.
  • An attempt to serialize and then deserialize a class containing transient fields will result in NULLs where the transient data should be. This is an excellent way to prevent time, environment-based, or sensitive variables from being carried over and used improperly.