CVE-2026-93576: netty CRLF Injection

Vulnerability summary

CVE-2026-93576 is a high (CVSS 7.5) CRLF Injection vulnerability in netty. EPSS estimates a 0.27% chance of exploitation in the next 30 days, higher than 17.8% of scored vulnerabilities.

Timeline

1. 18-09-2026
   PublishedVulnerability first disclosed.
2. 25-09-2026
   Last modifiedVulnerability information updated.

Description

A flaw was found in Netty netty-codec-smtp. The component does not properly validate Carriage Return (CR) and Line Feed (LF) characters in the SMTP command-name field. A remote attacker, if an application routes untrusted input into this field, can embed CR/LF characters to inject arbitrary SMTP commands. This can lead to SMTP command smuggling, allowing for unauthorized email relay or spoofing of sender/recipient addresses. While the impact is significant, the real-world exploitability is considered lower as applications typically do not place user-controlled data in the command-name field.

• CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.