Key Takeaways1. CVE-2016-10033 in PHPMailer permits attackers to execute arbitrary code via command injection within the mail() perform.2. The vulnerability is being exploited in reside cyberattacks, risking system compromise and knowledge breaches.3. Organizations should repair this by July 28, 2025, after CISA’s July 7 warning.4. Improve to PHPMailer v5.2.18+ or discontinue use of susceptible variations instantly.
CISA has issued an pressing warning concerning a vital command injection vulnerability in PHPMailer that’s being actively exploited in cyberattacks.
The vulnerability, tracked as CVE-2016-10033, poses important dangers to net functions worldwide that depend on the favored PHP-based e mail library.
CISA has added this vulnerability to its Recognized Exploited Vulnerabilities (KEV) catalog on July 7, 2025, with organizations required to implement fixes by July 28, 2025.
PHPMailer Command Injection Vulnerability
The PHPMailer command injection vulnerability stems from insufficient enter sanitization throughout the library’s core performance.
Particularly, the flaw impacts the mail() perform within the class.phpmailer.php script, the place user-supplied enter isn’t correctly validated earlier than being processed.
This safety weak point permits attackers to inject malicious instructions that execute throughout the software’s context, probably main to finish system compromise.
The vulnerability is assessed underneath CWE-77 (Improper Neutralization of Particular Components utilized in a Command) and CWE-88 (Improper Neutralization of Argument Delimiters in a Command), highlighting the elemental enter validation failures that allow the assault.
When exploitation makes an attempt fail, they may end up in denial-of-service circumstances, disrupting regular software operations.
The technical nature of this vulnerability makes it significantly harmful as PHPMailer is extensively built-in into content material administration programs, net functions, and enterprise software program options.
Cybercriminals are leveraging this vulnerability to execute arbitrary code on susceptible programs, although the precise particulars of present assault campaigns stay underneath investigation.
The command injection happens when malicious enter bypasses the library’s safety controls, permitting attackers to run unauthorized instructions on the internet hosting server.
Whereas CISA has not confirmed whether or not this vulnerability is being utilized in ransomware campaigns, the potential for such exploitation stays a big concern given the widespread deployment of PHPMailer.
The vulnerability’s exploitation can result in knowledge breaches, unauthorized entry to delicate data, and full server takeover.
Organizations utilizing affected PHPMailer variations face rapid dangers, significantly these with internet-facing functions that course of consumer enter via e mail performance.
Danger FactorsDetailsAffected ProductsPHPMailer variations previous to v5.2.18Web functions utilizing susceptible PHPMailer libraryContent administration programs integrating PHPMailerImpactComplete system compromiseExploit Stipulations– Goal system operating susceptible PHPMailer version- Software accepting consumer enter via e mail functionality- Entry to mail() perform in school.phpmailer.php- Capacity to produce malicious enter to the applicationCVSS 3.1 Score9.8 (Crucial)
Mitigation Methods
CISA strongly recommends that organizations instantly apply vendor-provided mitigations and safety patches.
For cloud service deployments, directors ought to observe BOD 22-01 steering to make sure complete safety.
Organizations unable to implement out there mitigations ought to contemplate discontinuing use of susceptible PHPMailer implementations till correct safety measures might be deployed.
The vulnerability impacts PHPMailer variations previous to v5.2.18, and organizations ought to improve to the most recent safe model instantly.
Safety groups ought to prioritize this vulnerability of their patching schedules and conduct thorough assessments of all functions using PHPMailer performance to make sure full remediation throughout their infrastructure.
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