Cross-site Scripting (XSS)Weakness · CWE-79

CVE-2026-8599

MEDIUM · 6.4 CVSS v3.1 Published 2026-06-09

Mitigation only

No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.

See remediation →

70/100

Remediation priority · Elevated

Remotely reachable Zero-click

Official description

NVD · unedited

The MailerPress – Email Marketing, Newsletter, Email Automation & WooCommerce Emails plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Campaign HTML Content Field in all versions up to, and including, 2.0.4 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with author-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The public-facing campaign preview endpoint (/mp-email/{id}-slug/) is not affected by this vulnerability, as it applies a Content-Security-Policy header blocking all inline scripts; exploitation is limited to the admin dashboard preview.

Technical summary

dbcve analysis · high confidence

Stored Cross-Site Scripting (XSS) vulnerability in the MailerPress WordPress plugin's Campaign HTML Content Field. Authenticated attackers with author-level or higher privileges can inject malicious scripts due to insufficient input sanitization and output escaping; scripts execute when users access injected pages in the admin dashboard.

MitigationUpdate MailerPress plugin to version beyond 2.0.4; if no patched version is available, implement proper input sanitization (e.g., wp_kses, esc_html) and output escaping (e.g., esc_attr, esc_html) on the Campaign HTML Content Field and review all user-controllable input points.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown

From the vector

Attack vector: Network
Complexity: Low
Privileges: Low
User interaction: None
Scope: Changed
Confidentiality: Low
Integrity: Low
Availability: None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

Am I affected?

dbcve checks

Work through these to decide whether this CVE applies to you.

Verify MailerPress plugin is installed

Navigate to WordPress admin dashboard > Plugins > Installed Plugins and check if MailerPress appears in the list

Affected if MailerPress plugin is installed and active
Identify MailerPress version

In Plugins list, check the version column for MailerPress; alternatively check the plugin header in mailerpress.php file if accessible via file manager or FTP

Affected if Installed version is unpatched (compare to any patched version released after CVE disclosure)
Check for author-level user accounts

Navigate to WordPress admin > Users and review user roles; note that author role or higher is required for exploitation

Affected if Any user account with author-level or higher access exists in the WordPress installation
Inspect Campaign HTML Content Field for malicious scripts

Navigate to MailerPress > Campaigns, open any campaign, and examine the HTML Content Field input; look for script tags, iframe tags, event handlers (onload, onerror, onclick), or encoded JavaScript patterns

Affected if The Campaign HTML Content Field contains unsanitized script tags or event handler attributes
Test admin preview for script execution

Navigate to MailerPress > Campaigns > create or edit a campaign > click preview button; inspect the page source or use browser developer tools to check if raw HTML/script tags execute or appear unescaped

Affected if Preview renders HTML content without proper escaping (script tags execute or appear as raw HTML in page source)

A user is affected if MailerPress is installed, the installed version is unpatched, and a campaign with malicious content in the HTML Content Field exists and triggers unsanitized script execution when previewed in the admin dashboard.

Generated from the published advisory. Verify against your own configuration.

Remediation

From vendor data

Mitigation available No clean upgrade yet — mitigate in the meantime

Mitigation

Update MailerPress plugin to version beyond 2.0.4; if no patched version is available, implement proper input sanitization (e.g., wp_kses, esc_html) and output escaping (e.g., esc_attr, esc_html) on the Campaign HTML Content Field and review all user-controllable input points.

Have this fixed Scoped from the published advisory

Consultation1.0 h
Implementation2.0 h
Testing1.0 h
Review / QA1.0 h

5.0 hours of engineering $890

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Scan for this in your stack

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References

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-8599 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2026-8599?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here

Verified mitigations, workarounds, and config changes
Version or environment caveats, and links to real fixes
No weaponised exploit code, or anything meant to cause harm
No spam, self-promotion, credentials, or personal data

At a glance

A fix existsA vendor remedy is published

Severity 6.4 Medium

Exploit likelihood EPSS, next 30 days 0.2%

Remediation

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Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

Check your environment

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

CVSS breakdown

Am I affected?

Remediation

References