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Mpl Publisher - Cross-Site Scripting (XSS) (CVE-2021-39343)

CVE-2021-39343

Vulnerability CVE-2021-39343 PLUGIN mpl-publisher MEDIUM

The MPL-Publisher WordPress plugin is vulnerable to Stored Cross-Site Scripting due to insufficient input validation and sanitization via several parameters found in the ~/libs/PublisherController.php file which allowed attackers with administrative user access to inject arbitrary web scripts, in versions up to and including 1.30.2. This affects multi-site installations where unfiltered_html is disabled for administrators, and sites where unfiltered_html is disabled.

CVE-2021-39343

MEDIUM CVSS 5.5 Published 2021-10-19 Updated 2026-06-17
AI Risk Elevated (58/100) Active Exploit: No strong signal Published Exploit: Public exploit references found Priority: P3 Priority
Severity Band MEDIUM
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N
Affected Components 1
Reference Links 3
AI Risk Engine Elevated (58/100)
Exploitability Medium
Active Exploitation No strong signal
Published Exploit Status Public exploit references found

Threat Timeline

  1. 2021-10-19 CVE published and first recorded in the threat feed.
  2. 2026-06-17 Record updated with latest vulnerability metadata.
  3. 2026-04-12 AI technical context refreshed for mitigation and impact guidance.
  4. Now Monitoring for follow-up changes, linked references, and new related CVEs.

AI Context

Machine-generated threat intelligence

AI Updated 177 days ago

AI enriched 177 days ago (2026-04-12 03:16 UTC)

Technical Summary

The MPL-Publisher WordPress plugin is vulnerable to Stored Cross-Site Scripting due to insufficient input validation and sanitization via several parameters found in the ~/libs/PublisherController.php file which allowed attackers with administrative user access to inject arbitrary web scripts, in versions up to and including 1.30.2. This affects multi-site installations where unfiltered_html is disabled for administrators, and sites where unfiltered_html is disabled.

Potential Impact

Severity is MEDIUM (CVSS 5.5). Depending on deployment context, affected components may be exposed to unauthorized actions or data integrity risk.

Exploitability Assessment

Exploitability is assessed as Medium based on published exploit references.

Primary risk drivers: published exploit references

Mitigation Recommendations

Validate affected product versions, prioritize patching, and monitor references for vendor remediation guidance. If immediate patching is not possible, apply compensating controls and limit exposure of vulnerable surfaces.

Detection & Monitoring

Track authentication anomalies, unexpected file writes, and suspicious plugin API activity around affected components.

Business Impact Lens

AI risk score 58/100 (Elevated, Medium) with priority P3 Priority. Prioritize remediation where affected components process customer data, admin sessions, or Internet-exposed workflows.

Affected Products

Mpl Publisher PLUGIN · mpl-publisher Affected: <= 1.30.2 Fixed version not specified

References

What to do about this

Patch on your next cycle Worth fixing, but not ahead of other work.

Fix it

Update Mpl Publisher to the latest available version.

Where the vendor has not published a fix yet, disable the plugin until they do.

Cannot update today? Request / payload inspection (WAF) in Hack Halt ProSecure blocks this class of attack before WordPress processes the request.

Inspect request parameters and bodies for injection, traversal and file-inclusion payloads, and refuse the request rather than logging it.

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Not sure if you are affected?

Scan your site to see whether it runs Mpl Publisher, and at which version.

Free, no installation, no account. It reads what your site already publishes, then tells you which plugins carry known vulnerabilities and what to do about each one.

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Am I affected by this vulnerability?

You are affected if your site runs Mpl Publisher.

How do I fix it?

Update Mpl Publisher to the latest available version. Where the vendor has not yet published a fix, remove or disable the plugin until they do. Until you can update, Request / payload inspection (WAF) in Hack Halt ProSecure contains this class of attack at the request layer.

What can an attacker actually do?

This is a Cross-Site Scripting (XSS) flaw. An attacker who exploits it can run script in a visitor's browser, stealing sessions or planting an administrator account.

WordPress security that blocks attacks before they land.

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