CVE-2026-48019 in Laravel
Summary
by MITRE • 09/05/2026
Laravel is a web application framework. Prior to versions 12.60.0 and 13.10.0, a CRLF injection vulnerability in Laravel's email validation, in combination with how Symfony Mailer and Symfony Mime handle certain character sequences, may allow an unauthenticated attacker to interfere with outbound email processing in applications that send mail to user-supplied addresses. This issue has been patched in versions 12.60.0 and 13.10.0.
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Analysis
by VulDB Data Team • 09/05/2026
The vulnerability identified involves a Carriage Return Line Feed (CRLF) injection flaw within the Laravel web application framework, specifically affecting email validation logic prior to version 12.60.0 in the LTS branch and before version 13.10.0 in the current release track. This security issue arises from an interaction between Laravel's input sanitization mechanisms for email addresses and the underlying behavior of Symfony Mailer and Symfony Mime components when processing specific character sequences. The core technical flaw lies in the insufficient validation or encoding of user-supplied data before it is passed to the mail handling subsystems, allowing special characters such as carriage returns (CR) and line feeds (LF) to be interpreted literally rather than being escaped or rejected.
From a technical perspective, CRLF injection occurs when an attacker injects newline characters into input fields that are subsequently used in HTTP headers or email message construction. In the context of Laravel's mail functionality, if an application allows users to specify recipient addresses dynamically without rigorous sanitization, an attacker can append malicious header injections to these addresses. Because Symfony Mailer and Mime handle certain character sequences by interpreting them as structural delimiters for email parts, the injected CRLF characters can break out of the intended To or CC fields. This enables the injection of arbitrary headers such as Bcc, Subject, or even Content-Type modifications into the outgoing email message structure.
The operational impact of this vulnerability is significant for applications that facilitate user-driven email sending features, such as contact forms, password reset mechanisms, notification systems, or any service where end-users can influence recipient addresses. An unauthenticated attacker exploiting this flaw could manipulate outbound emails to bypass intended recipients by adding blind carbon copy (Bcc) fields containing malicious targets. This facilitates unauthorized mass mailing, potential phishing campaigns leveraging the application's trusted domain reputation, and data exfiltration if sensitive information is inadvertently included in injected headers or body content due to header manipulation altering message parsing behavior.
This vulnerability aligns with Common Weakness Enumeration CWE-74, which describes Improper Neutralization of Special Elements used in an OS Command (CRLF Injection), although it specifically applies here within the context of email protocol construction rather than direct operating system command execution. It also maps to MITRE ATT&CK technique T1534, Internal Spearphishing, as the attacker can leverage the compromised application's identity to send deceptive emails that appear legitimate to recipients due to the trusted sender domain. The exploitation vector is typically remote and unauthenticated, requiring only interaction with a web interface or API endpoint exposed by the vulnerable Laravel application.
Mitigation strategies primarily involve upgrading the Laravel framework to version 12.60.0 or later for long-term support releases, or version 13.10.0 or later for current release tracks, where this issue has been patched through enhanced input validation and stricter handling of special characters in email fields. For applications unable to upgrade immediately, developers should implement strict server-side validation that rejects any email addresses containing non-printable ASCII characters, including carriage returns (ASCII 13) and line feeds (ASCII 10). Additionally, employing output encoding functions specifically designed for email headers can prevent the interpretation of injected sequences as structural delimiters. It is also advisable to review all code paths where user-supplied data is passed directly to mailer services without intermediate sanitization layers.