CVE-2023-33328Network attack vector

Admin stored XSS via unsanitized settings

Published May 28, 2023 · Updated Apr 28, 2026

Cross-site scripting in PluginOps MailChimp Subscribe Form through 4.0.9.1 allows remote authenticated users to inject scripts via administrative settings. The plugin fails to sanitize submitted settings and escape them when rendered, so stored payloads execute in pages viewed by users. Administrator-level access is required, and impact is limited to script-driven confidentiality, integrity, and availability effects in affected WordPress sites.

CVSS severity4.8
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Cross-site scripting in PluginOps MailChimp Subscribe Form through 4.0.9.1 allows remote authenticated users to inject scripts via administrative settings. The plugin fails to sanitize submitted settings and escape them when rendered, so stored payloads execute in pages viewed by users. Administrator-level access is required, and impact is limited to script-driven confidentiality, integrity, and availability effects in affected WordPress sites.

The record

CVE
CVE-2023-33328
Published
May 28, 2023
Updated
Apr 28, 2026
Vendor
PluginOps
Product
MailChimp Subscribe Form, Optin Builder, PopUp Builder, Form Builder
Classifications
CWE-79, CAPEC-592, T1189
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 28, 2023CVE publishedPublication date reported by the CVE source.
  2. Apr 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a <=4.0.9.1 changes=[{"at":"4.0.9.2","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

PluginOps · MailChimp Subscribe Form, Optin Builder, PopUp Builder, Form Builderversion=n/a <=4.0.9.1 changes=[{"at":"4.0.9.2","status":"unaffected"}]

Published CVSS scores

4.8NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
5.9PatchstackCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CAPEC-592Stored XSS
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo