CVE-2025-54940

Advanced Custom Fields <= 6.4.2. - HTML Injection

2025-08-08 00:00

Strategic Overview

Status: Patched in 6.4.3
Affected Plugin: Advanced Custom Fields (ACF®)
Affected Version: <= 6.4.2
CVSS: 4.1Medium
Weakness type: CWE-20 · Improper Input Validation
CVE: CVE-2025-54940

View all Advanced Custom Fields (ACF®) vulnerabilities

At a glance

CVE-2025-54940 is a medium-severity Improper Input Validation vulnerability in the Advanced Custom Fields (ACF®) WordPress plugin, affecting versions <= 6.4.2. It carries a CVSS score of 4.1 (reachable over the network; low attack complexity). The issue is fixed in version 6.4.3; sites on affected versions should update now. Disclosed August 2025, reported by Shogo Kumamaru.

Vulnerability Overview

The Advanced Custom Fields (ACF®) plugin for WordPress is vulnerable to HTML Injection in all versions up to, and including, 6.4.2. This is due to the plugin nor properly neutralizing unsafe HTML. This makes it possible for authenticated attackers, with administrator-level access and above, to inject potentially malicious HTML.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no interaction from a victim user.

CWE-20: Improper Input Validation

Reaching this weakness in Advanced Custom Fields (ACF®) <= 6.4.2 takes a caller who can reach the endpoint. Improper input validation means the application accepts input without confirming it has the form, type or range the code downstream assumes.

The concrete impact depends on where the unvalidated value lands, which is why records in this class range from cosmetic bugs to full compromise. For Advanced Custom Fields (ACF®) the fix is 6.4.3: builds <= 6.4.2 are affected, anything from 6.4.3 onward is not.

Remediation

Update to version 6.4.3, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Advanced Custom Fields (ACF®): WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Advanced Custom Fields (ACF®) 6.4.3 closes this, and updating the plugin is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2025-54940 https://www.wordfence.com/threat-intel/vulnerabilities/id/0f5a48ec-da62-4a9d-a8a5-30da7b6d23f6 https://nvd.nist.gov/vuln/detail/CVE-2025-54940

Related records

Other vulnerabilities in Advanced Custom Fields (ACF®)

CVSS Vector

4.1

CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:L/A:N

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredHigh
User InteractionNone
ScopeChanged
ConfidentialityNone
IntegrityLow
AvailabilityNone

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