CVE-2023-4386

Essential Blocks <= 4.2.0 - Unauthenticated PHP Object Injection via queries

2023-09-13 00:00
Marco Wotschka

Strategic Overview

Status
Patched in 4.2.1
Affected Plugin
Gutenberg Essential Blocks – Page Builder for Gutenberg Blocks & Patterns
Affected Version
<= 4.2.0
CVSS
8.1High
Weakness type
CWE-502 · Deserialization of Untrusted Data
CVE
CVE-2023-4386
View all Gutenberg Essential Blocks – Page Builder for Gutenberg Blocks & Patterns vulnerabilities

At a glance

CVE-2023-4386 is a high-severity Deserialization of Untrusted Data vulnerability in the Gutenberg Essential Blocks WordPress plugin, affecting versions <= 4.2.0. It carries a CVSS score of 8.1 (reachable over the network; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 4.2.1; sites on affected versions should update now. Disclosed September 2023, reported by Marco Wotschka.

Vulnerability Overview

The Essential Blocks plugin for WordPress is vulnerable to PHP Object Injection in versions up to, and including, 4.2.0 via deserialization of untrusted input in the get_posts function. This allows unauthenticated attackers to inject a PHP Object. No POP chain is present in the vulnerable plugin. If a POP chain is present via an additional plugin or theme installed on the target system, it could allow the attacker to delete arbitrary files, retrieve sensitive data, or execute code.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, and no privileges on the target site, 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

Reaching this weakness in Gutenberg Essential Blocks <= 4.2.0 takes no account at all. 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 Gutenberg Essential Blocks the fix is 4.2.1: builds <= 4.2.0 are affected, anything from 4.2.1 onward is not.

Remediation

Update to version 4.2.1, or a newer patched version

How does WordSec protect against this?

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: 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: Gutenberg Essential Blocks 4.2.1 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Scanner
  • Login Security

External References

https://www.cve.org/CVERecord?id=CVE-2023-4386https://www.wordfence.com/threat-intel/vulnerabilities/id/af468f83-d6ad-474c-bf7f-c4eeb6df1b54https://nvd.nist.gov/vuln/detail/CVE-2023-4386

Related records

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