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The vulnerability in PHPMailer (CVE-2016-10033) allows remote attackers to execute arbitrary code due to improper input sanitization in the `mailSend` function when using the default `isMail` transport. The flaw arises when a crafted `Sender` property containing a backslash followed by a double quote (\") is processed. This enables attackers to inject additional parameters into the underlying `mail()` command, effectively bypassing security checks. Since PHPMailer passes user-supplied input directly to the system’s mail function, an attacker can manipulate command execution. The issue affects versions before 5.2.18 and is particularly dangerous in configurations where PHPMailer processes untrusted input, such as web forms.
DailyCVE Form:
Platform: PHPMailer
Version: <5.2.18
Vulnerability: RCE
Severity: Critical
Date: Dec 30, 2016
Prediction: Patched (5.2.18 released)
What Undercode Say:
Exploit PoC (example): curl -X POST -d "sender=attacker\\" -oX/tmp/exploit\"@evil.com" http://target/form
How Exploit:
- Crafted `Sender` field injects OS commands.
- Bypasses sanitization via `\”` sequence.
- Leverages `mail()` function parameter injection.
Protection from this CVE:
- Upgrade to PHPMailer ≥5.2.18.
- Disable `isMail` transport if unused.
- Sanitize all user-supplied inputs.
Impact:
- Full server compromise.
- Arbitrary command execution.
- Data exfiltration possible.
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
