Laravel CRLF Injection Vulnerability Affects Email

A high-severity CRLF injection vulnerability, CVE-2026-48019, affects the Laravel framework. Attackers could exploit this flaw to interfere with outbound email processing in affected applications.

The issue impacts Laravel versions up to 13.9.0 and versions before 12.60.0, and has been patched in 13.10.0 and 12.60.0.

The vulnerability stems from improper neutralization of carriage return and line feed (CRLF) sequences in email validation logic, which is classified as CWE-93.

In certain scenarios, Laravel applications rely on user-supplied email addresses for functionality such as account registration, password resets, or contact forms.

If these inputs are not adequately sanitized before being passed to the underlying mail transport layer, they may allow injection of malicious control characters.

This issue becomes particularly significant when combined with the behavior of the Symfony Mailer and Symfony Mime components, which Laravel uses to handle email delivery.

Laravel CRLF injection Vulnerability

Specially crafted input containing CRLF sequences can manipulate email headers or structure, enabling attackers to alter message content or routing.

In practical terms, this means an attacker could potentially inject additional recipients, modify message bodies, or trigger unintended email transmissions.

Security researchers note that exploitation does not require authentication or user interaction, increasing the risk for publicly exposed applications.

While the attack complexity is rated high, successful exploitation could result in significant impacts on confidentiality and integrity.

For example, sensitive emails intended for legitimate users could be redirected, or attackers could abuse the application’s mail server for relay attacks or phishing campaigns.

The CVSS v3.1 base score reflects this risk with a vector of CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L, indicating network-based exploitation with no privileges required and a scope change affecting downstream systems.

Availability impact is considered low, but confidentiality and integrity risks remain high.

From an operational standpoint, affected organizations should treat this vulnerability as a priority, especially if their applications process untrusted email input.

Systems handling authentication workflows, transactional notifications, or user communications are particularly exposed.

Misuse of outbound email infrastructure could also lead to reputational damage, blocklisting of mail servers, or regulatory concerns depending on the nature of the data involved.

The Laravel maintainers have released patches addressing the issue, and users are strongly advised to upgrade to version 13.10.0 or later, or 12.60.0 or later.

In addition to patching, developers should implement strict input validation and sanitization for email fields and review how user input flows into mail-related functions.

The flaw, disclosed by security researcher OmarXtream in GitHub advisory GHSA-5vg9-5847-vvmq, highlights persistent risks in routine input validation mechanisms.

As email remains a critical communication channel for modern applications, flaws in its handling continue to present attractive targets for attackers seeking indirect exploitation paths.

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