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Deserialization of Untrusted DataWeakness · CWE-502

CVE-2026-12583

HIGH · 8.1 CVSS v3.1 Published 2026-07-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
90/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click 5 weeks old

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.

NVD · unedited
The Newsletters WordPress plugin before 4.15 does not prevent deserialization of untrusted input that is stored through a public form, allowing unauthenticated attackers to inject a PHP object and, via a property-oriented gadget chain bundled with the Newsletters WordPress plugin before 4.15, write arbitrary files and execute code on the server.

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.

dbcve analysis · high confidence

The Newsletters WordPress plugin before 4.15 fails to validate input submitted through its public subscription forms, allowing unauthenticated attackers to inject malicious PHP objects via insecure deserialization. This enables remote code execution through a property-oriented gadget chain already present in the plugin.

MitigationUpgrade to Newsletters plugin version 4.15 or later immediately. If immediate patching is not feasible, block or restrict access to the public form endpoints using a WAF or web server access controls as a temporary measure.

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

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.

From the vector
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

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.

dbcve checks

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

  1. Locate the Newsletters plugin installation directory
    Check your WordPress wp-content/plugins/ directory for a folder named 'newsletters' or 'newsletters-lite'. If using Composer or a managed hosting setup, verify the plugin files are present in the equivalent plugins path.
    Affected if The plugin is not present in the environment.
  2. Determine the installed plugin version
    Open the main plugin file (typically newsletters/newsletters.php or newsletters-lite/newsletters.php) and locate the 'Version' header comment in the file header. Alternatively, check the WordPress admin dashboard under Plugins > Installed Plugins and find the Newsletters plugin version number.
    Affected if The version number is lower than 4.15 (e.g., 4.14, 4.13, etc.).
  3. Verify public subscription form functionality is enabled
    Access the WordPress admin panel, navigate to the Newsletters plugin settings, and check whether the public subscription/subscribe form feature is turned ON or enabled. This setting is typically found under the plugin's Form Settings or Subscription Options.
    Affected if The subscription form is enabled and publicly accessible.
  4. Confirm the subscription form endpoint is reachable
    Attempt to access common subscription form URLs on your site, such as /?na=signup, /?nltr=..., or /wp-json/newsletters/v1/subscribe. Use a web browser or curl to test if these endpoints return a subscription form or accept POST requests.
    Affected if The form endpoint responds and accepts input without requiring authentication.

Your environment is affected if the Newsletters plugin version is below 4.15 AND the public subscription form is enabled and accessible to unauthenticated users.

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

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to Newsletters plugin version 4.15 or later immediately. If immediate patching is not feasible, block or restrict access to the public form endpoints using a WAF or web server access controls as a temporary measure.

Recommended fix Moderate confidence

Newsletters WordPress plugin version 4.15 or later

  1. 1. Back up the entire WordPress site (database and files) before making any changes
  2. 2. Log in to the WordPress admin dashboard
  3. 3. Navigate to Plugins > Installed Plugins
  4. 4. Find the 'Newsletters' plugin in the list
  5. 5. If an update is available, click 'Update Now' to upgrade to version 4.15 or later
  6. 6. Alternatively, download the Newsletters plugin version 4.15 or newer from wordpress.org
  7. 7. Deactivate and delete the existing Newsletters plugin, then upload and activate the new version
  8. 8. Verify the plugin version in Plugins > Installed Plugins confirms version 4.15 or higher

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation5.0 h
  • Implementation8.0 h
  • Testing5.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,910
Get help mitigating

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Scan for this in your stack

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

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-12583 in production — separate from our analysis above.

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