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FluentSMTP – WP SMTP Plugin with Amazon SES, SendGrid, MailGun, Postmark, Google and Any SMTP Provider <= 2.2.82 — Unauthenticated PHP Object Injection

CVE-2024-9511Published · Updated

Action summary

Affected: ≤2.2.82Update to 2.2.83 or newer

All remediation steps
Severity
Critical9.8
CVSS
9.8
CVSS 3.1 · CNA (Wordfence)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
What does this vector mean?
AV:N Attack vector
Network
AC:L Attack complexity
Low
PR:N Privileges required
None
UI:N User interaction
None
S:U Scope
Unchanged
C:H Confidentiality
High
I:H Integrity
High
A:H Availability
High
Weakness
CWE-502 PHP Object Injection
Required access
No account needed
Exploit prediction (EPSS)
No score
CISA KEV
Not listed

Am I affected?

FluentSMTP – WP Mail SMTP Plugin with Amazon SES, SendGrid, Mailgun, Postmark, Cloudflare, toSend, Gmail and Any SMTP fluent-smtp

  1. Affected≤ 2.2.82
  2. Patched in2.2.83

Update to 2.2.83 or newer.

You are affected if you run ≤ 2.2.82. Version 2.2.83 and later are not affected by this issue.

  • Check your version: in wp-admin go to Plugins → Installed Plugins and read the version under FluentSMTP – WP Mail SMTP Plugin with Amazon SES, SendGrid, Mailgun, Postmark, Cloudflare, toSend, Gmail and Any SMTP.
  • No admin access? Run a passive check of your site. It reads public files only.
  • No account is needed to exploit this. Treat any exposed site on an affected version as at risk.

What to do

  1. Update to version 2.2.83, or a newer patched version
  2. Rotate administrator passwords and application secrets if the site ran a vulnerable version while publicly reachable.
  3. Watch FluentSMTP – WP Mail SMTP Plugin with Amazon SES, SendGrid, Mailgun, Postmark, Cloudflare, toSend, Gmail and Any SMTP to get an email when the next vulnerability is published.

Advisory

Source description from Wordfence Intelligence, credited to Leo.

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.

Exploits & references

Proof-of-concept & detection

No public proof-of-concept or detection template is known for this vulnerability.

Advisories & patches

More in FluentSMTP – WP Mail SMTP Plugin with Amazon SES, SendGrid, Mailgun, Postmark, Cloudflare, toSend, Gmail and Any SMTP

All 6
More vulnerabilities in FluentSMTP – WP Mail SMTP Plugin with Amazon SES, SendGrid, Mailgun, Postmark, Cloudflare, toSend, Gmail and Any SMTP
SeverityVulnerabilityCVEPublished
High7.2Unauthenticated Stored Cross-Site Scripting via Recipient Display Name (to.name) in Email Logs
≤2.2.95Update to 2.3.0
CVE-2026-16636
Medium4.3Cross-Site Request Forgery
≤2.2.80Update to 2.2.81
CVE-2025-24739
High7.2Unauthenticated Stored Cross-Site Scripting via Email Subject
≤2.2.4Update to 2.2.5
CVE-2023-3087
Low3.8Authenticated (Author+) Stored Cross-Site Scripting via Email Logs
≤2.2.2Update to 2.2.3
CVE-2023-0219
Medium5.5Authenticated (Admin+) Stored Cross-Site Scripting
<2.0.1Update to 2.0.1
CVE-2021-24528

Same weakness (PHP Object Injection)

All PHP Object Injection
Other PHP Object Injection vulnerabilities
SeverityVulnerabilityCVEPublished
High7.2Unauthenticated Stored Cross-Site Scripting via Comment User-Agent HeaderCVE-2026-120688
Critical9.8Unauthenticated Arbitrary File Upload via File Upload via Public Form SubmissionCVE-2026-125055
Critical9.8Unauthenticated PHP Object Injection to Remote Code Execution via 'form' ParameterCVE-2026-119077
Medium5.3Unauthenticated Sensitive Information Exposure in 'search' Parameter
Customer Reviews for WooCommerce≤5.127.0Update to 5.128.0
CVE-2026-121518

Timeline

  1. CVE published

    Severity critical, CVSS 9.8

  2. Record last updated

Sources & licenses

Wordfence record
Vulnerability data
Wordfence Intelligence. Copyright 2012-2026 Defiant Inc. Licensed under the CC BY-SA 4.0.
CVE® identifiers
Copyright 1999-2026 The MITRE Corporation. Used under the CVE Program. CVE® is a registered trademark of The MITRE Corporation.
CVSS / CWE
National Vulnerability Database (NVD), shown unmodified. This product uses the NVD API but is not endorsed or certified by the NVD.
VulnCrest content
Summary, remediation guidance and page layout © VulnCrest. Not sourced from NVD.

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