dbcve.org
Deserialization of Untrusted DataWeakness · CWE-502

CVE-2024-9511

CRITICAL · 9.8 CVSS v3.1 Published 2024-11-23
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 FluentSMTP – WP SMTP Plugin with Amazon SES, SendGrid, MailGun, Postmark, Google and Any SMTP Provider plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 2.2.82 via deserialization of untrusted input in the 'formatResult' function. This makes it possible for unauthenticated attackers to inject a PHP Object. No known POP chain is present in the vulnerable software. If a POP chain is present via an additional plugin or theme installed on the target system, it could allow the attacker to delete arbitrary files, retrieve sensitive data, or execute code. The vulnerability was partially patched in version 2.2.82.

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 FluentSMTP WordPress plugin is vulnerable to PHP Object Injection via unsafe deserialization in the formatResult function. Unauthenticated attackers can inject arbitrary PHP objects. While no POP chain exists in the plugin itself, if another installed plugin/theme provides one, attackers could achieve remote code execution.

MitigationUpdate to the latest version of FluentSMTP immediately. The vulnerability was partially patched in 2.2.82, so ensure you have the most recent release that fully addresses the deserialization issue.

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
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/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. Verify FluentSMTP plugin installation and version
    Navigate to WordPress admin > Plugins > Installed Plugins, find FluentSMTP, and note the version number. Alternatively, check the plugin file /wp-content/plugins/fluent-smtp/readme.txt for the Version: field.
    Affected if The installed version is lower than 2.2.82 (the partial patch) or below the latest patched release.
  2. Locate the vulnerable formatResult function
    Access the plugin files via file manager or FTP. Navigate to /wp-content/plugins/fluent-smtp/ and search for the function named 'formatResult' in PHP files.
    Affected if The function exists and contains an unserialize() call on user-controlled or external data without proper validation.
  3. Confirm unsafe deserialization in formatResult
    Open the file containing formatResult and examine the code. Look for patterns like unserialize($_POST[...]), unserialize($_GET[...]), or unserialize applied to data from HTTP request parameters.
    Affected if The function uses unserialize() on data that originates directly or indirectly from unauthenticated HTTP requests.
  4. Verify the attack surface is exposed to unauthenticated users
    Check if the formatResult function is hooked to an action or endpoint that does not require authentication. Search for add_action or add_hook references to formatResult and examine the associated hook's capability requirements.
    Affected if The vulnerable function can be reached by unauthenticated (not-logged-in) users.

You are affected if FluentSMTP is installed with a version below 2.2.82, the formatResult function contains unsafe unserialize(), and the function is 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

Update to the latest version of FluentSMTP immediately. The vulnerability was partially patched in 2.2.82, so ensure you have the most recent release that fully addresses the deserialization issue.

Recommended fix High confidence

FluentSMTP version 2.2.83 or latest stable release (version after 2.2.82)

  1. Upgrade the FluentSMTP plugin to the latest available version from the WordPress plugin repository
  2. After upgrading, verify the plugin version in WordPress admin under Plugins > Installed Plugins
  3. Review the plugin settings to ensure configuration remains intact after upgrade
  4. If available, check the plugin changelog for any security-related notes about the complete fix
Caveat Standard minor version upgrade - review any setting changes in changelog before upgrading on production sites

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

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
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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-2024-9511 in production — separate from our analysis above.

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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