CVE-2016-10033
Published: July 7, 2025
Official Description
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.
CISA KEV Advisory
PHPMailer Command Injection Vulnerability
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.
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Risk Analysis
PHPMailer contains a command injection vulnerability due to improper sanitization of user-supplied input in the 'mail()' function. This flaw can allow an attacker to execute arbitrary code or cause a denial-of-service. The high EPSS score of 0.94470 indicates a significant likelihood of exploitation, making this a serious concern.
This vulnerability is actively exploited in the wild and is listed in CISA's KEV catalog, confirming its active use by threat actors.
Administrators should update PHPMailer to a patched version to address this command injection vulnerability and prevent arbitrary code execution.
Technical Analysis
CVE-2016-10033 requires local access, meaning attackers must already have a foothold on the target system.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
CISA has added CVE-2016-10033 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.
Affected Vendors & Products
Exploit & PoC Resources
All References (2)
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2016-10033 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
- !CISA KEV: Federal agencies must patch per BOD 22-01 timeline
- !Active exploitation confirmed — treat as P1