Vulnerability in Netty
CVE-2025-59419
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.
Vulnerability class: CRLF Injection
Published · last modified .
EPSS exploit prediction
EPSS: 0.016 (74.1th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 74th percentile — 74.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.016 · newest: 0.016 · change: -0.000
Affected products
- Netty — versions < 4.2.7.Final, >= 4.2.0.Alpha1, < 4.1.128.Final
Weakness classification (CWE)
Public proof-of-concept exploits
References
Frequently asked questions
- What is CVE-2025-59419?
- CVE-2025-59419 is a vulnerability in Netty, classified under CRLF Injection. Published 2025-10-15.
- Is CVE-2025-59419 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.