CVE-2025-64227

Client Invoicing by Sprout Invoices <= 20.8.7 - Unauthenticated PHP Object Injection

2025-09-02 00:00
Drew Webber (mcdruid)

Strategic Overview

Status
Patched in 20.8.8
Affected Plugin
Sprout Invoices – Client Invoicing & Estimates
Affected Version
<= 20.8.7
CVSS
8.1High
Weakness type
CWE-502 · Deserialization of Untrusted Data
CVE
CVE-2025-64227
View all Sprout Invoices – Client Invoicing & Estimates vulnerabilities

At a glance

CVE-2025-64227 is a high-severity Deserialization of Untrusted Data vulnerability in the Sprout Invoices WordPress plugin, affecting versions <= 20.8.7. 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 20.8.8; sites on affected versions should update now. Disclosed September 2025, reported by Drew Webber (mcdruid).

Vulnerability Overview

The Client Invoicing by Sprout Invoices plugin for WordPress is vulnerable to PHP Object Injection in versions up to, and including, 20.8.7 via deserialization of untrusted input. This makes it possible for unauthenticated attackers to inject a PHP Object. No known POP chain is present in the vulnerable software. 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 Sprout Invoices <= 20.8.7 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 Sprout Invoices the fix is 20.8.8: builds <= 20.8.7 are affected, anything from 20.8.8 onward is not.

Remediation

Update to version 20.8.8, 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: Sprout Invoices 20.8.8 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-2025-64227https://www.wordfence.com/threat-intel/vulnerabilities/id/418747c5-1c18-46e4-b15c-4815e7397cf2https://nvd.nist.gov/vuln/detail/CVE-2025-64227

Related records

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