CVE-2021-24579

Bold Page Builder <= 3.1.5 - PHP Object Injection

2021-08-02 00:00
dc11

Strategic Overview

Status
Patched in 3.1.6
Affected Plugin
Bold Page Builder
Affected Version
<= 3.1.5
CVSS
7.5High
Weakness type
CWE-502 · Deserialization of Untrusted Data
CVE
CVE-2021-24579
View all Bold Page Builder vulnerabilities

At a glance

CVE-2021-24579 is a high-severity Deserialization of Untrusted Data vulnerability in the Bold Page Builder WordPress plugin, affecting versions <= 3.1.5. It carries a CVSS score of 7.5 (reachable over the network; high confidentiality, integrity, availability impact). The issue is fixed in version 3.1.6; sites on affected versions should update now. Disclosed August 2021, reported by dc11.

Vulnerability Overview

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.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.

CWE-502: Deserialization of Untrusted Data

Bold Page Builder <= 3.1.5 carries this weakness at unserialize(), and reaching it takes a caller who can reach the endpoint. Deserialization of untrusted data means the application reconstructs objects from input a caller controls, letting the attacker choose which classes get instantiated and what their properties hold.

A workable chain turns deserialization into file writes, deletions or code execution, depending on what the loaded classes do in their magic methods. For Bold Page Builder the fix is 3.1.6: builds <= 3.1.5 are affected, anything from 3.1.6 onward is not.

Remediation

Update to version 3.1.6, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Bold Page Builder: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: Bold Page Builder 3.1.6 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Scanner
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2021-24579https://www.wordfence.com/threat-intel/vulnerabilities/id/09ac96f8-e138-48fe-bd95-5356fc222004https://nvd.nist.gov/vuln/detail/CVE-2021-24579

Related records

Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C