Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.128.Final and 4.2.7.Final, the SMTP codec in Netty contains an SMTP command injection vulnerability due to insufficient input validation for Carriage Return (\r) and Line Feed (\n) characters in user-supplied parameters. The vulnerability exists in io.netty.handler.codec.smtp.DefaultSmtpRequest, where parameters are directly concatenated into the SMTP command string without sanitization. When methods such as SmtpRequests.rcpt(recipient) are called with a malicious string containing CRLF sequences, attackers can inject arbitrary SMTP commands. Because the injected commands are sent from the server's trusted IP address, resulting emails will likely pass SPF and DKIM authentication checks, making them appear legitimate. This allows remote attackers who can control SMTP command parameters (such as email recipients) to forge arbitrary emails from the trusted server, potentially impersonating executives and forging high-stakes corporate communications. This issue has been patched in versions 4.1.129.Final and 4.2.8.Final. No known workarounds exist.

The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the UTSA-2025-991102 advisory.

    Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.128.Final     and 4.2.7.Final, the SMTP codec in Netty contains an SMTP command injection vulnerability due to     insufficient input validation for Carriage Return (\r) and Line Feed (\n) characters in user-supplied     parameters. The vulnerability exists in io.netty.handler.codec.smtp.DefaultSmtpRequest, where parameters     are directly concatenated into the SMTP command string without sanitization. When methods such as     SmtpRequests.rcpt(recipient) are called with a malicious string containing CRLF sequences, attackers can     inject arbitrary SMTP commands. Because the injected commands are sent from the server's trusted IP     address, resulting emails will likely pass SPF and DKIM authentication checks, making them appear     legitimate. This allows remote attackers who can control SMTP command parameters (such as email     recipients) to forge arbitrary emails from the trusted server, potentially impersonating executives and     forging high-stakes corporate communications. This issue has been patched in versions 4.1.129.Final and     4.2.8.Final. No known workarounds exist.

Tenable has extracted the preceding description block directly from the Unity Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote SUSE Linux SLED15 / SLED_SAP15 / SLES15 / SLES_SAP15 / openSUSE 15 host has packages installed that are affected by a vulnerability as referenced in the SUSE-SU-2025:4087-1 advisory.

    - CVE-2025-59419: fixed SMTP command injection vulnerability that allowed email forgery (bsc#1252097)

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Ubuntu 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 25.04 / 25.10 host has a package installed that is affected by a vulnerability as referenced in the USN-7843-1 advisory.

    It was discovered that Netty did not properly handle user input. A remote attacker could possibly use this     issue to forge arbitrary emails from a trusted server.

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.128.Final     and 4.2.7.Final, the SMTP codec in Netty contains an SMTP command injection vulnerability due to     insufficient input validation for Carriage Return (\r) and Line Feed (\n) characters in user-supplied     parameters. The vulnerability exists in io.netty.handler.codec.smtp.DefaultSmtpRequest, where parameters     are directly concatenated into the SMTP command string without sanitization. When methods such as     SmtpRequests.rcpt(recipient) are called with a malicious string containing CRLF sequences, attackers can     inject arbitrary SMTP commands. Because the injected commands are sent from the server's trusted IP     address, resulting emails will likely pass SPF and DKIM authentication checks, making them appear     legitimate. This allows remote attackers who can control SMTP command parameters (such as email     recipients) to forge arbitrary emails from the trusted server, potentially impersonating executives and     forging high-stakes corporate communications. This issue has been patched in versions 4.1.129.Final and     4.2.8.Final. No known workarounds exist. (CVE-2025-59419)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
277861	Unity Linux 20.1070e Security Update: netty (UTSA-2025-991102)	Nessus	Unity Linux Local Security Checks	medium
275262	SUSE SLED15 / SLES15 / openSUSE 15 Security Update : netty, netty-tcnative (SUSE-SU-2025:4087-1)	Nessus	SuSE Local Security Checks	medium
272031	Ubuntu 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 25.04 / 25.10 : Netty vulnerability (USN-7843-1)	Nessus	Ubuntu Local Security Checks	medium
271507	Linux Distros Unpatched Vulnerability : CVE-2025-59419	Nessus	Misc.	medium

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CVE-2025-59419

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