CVE-2016-10033 — PHPMailer Command Injection Vulnerability
Overview
PHPMailer contains a command injection vulnerability because it fails to sanitize user-supplied input. Specifically, this issue affects the 'mail()' function of 'class.phpmailer.php' script. An attacker can exploit this issue to execute arbitrary code within the context of the application. Failed exploit attempts will result in a denial-of-service condition.
Vulnerability details
- CVE ID
- CVE-2016-10033
- Vulnerability
- PHPMailer Command Injection Vulnerability
- Vendor
- PHP
- Affected products
- PHP: PHPMailer
- Severity
- HIGH
- Exploitation status
- Actively exploited in the wild (CISA KEV)
- Published
- 2025-07-07
Remediation guidance
CVE-2016-10033 is in CISA's Known Exploited Vulnerabilities (KEV) catalog — U.S. federal civilian agencies are required to remediate it under Binding Operational Directive 22-01. Treat it as a priority for every environment.
Apply the vendor's official security update for PHP the affected product as soon as possible. Where a patch is unavailable, apply vendor mitigations or isolate/segment exposed systems.
Hunt for indicators of compromise tied to this vulnerability and confirm logging/EDR coverage on affected assets.
Authoritative references
Remediate CVE-2016-10033 — and stay ahead of the next one
CVE-2016-10033 is listed in the CISA KEV catalog as actively exploited — treat remediation as urgent. Scan your domain free to see whether CVE-2016-10033 and other PHP issues affect you and get a prioritized remediation report (full report from ₹999) — or stream the full feed of 1,600+ actively-exploited CVEs straight into your SOC.
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