CVE-2026-93576

Summary

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.

Affected Software

Weaknesses

• CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')

Workarounds

See https://github.com/netty/netty/security/advisories/GHSA-5vh9-c45f-rf7p for fixed versions and remediation guidance.

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: yes
  • Technical Impact: partial

References

• https://access.redhat.com/security/cve/CVE-2026-93576
• https://bugzilla.redhat.com/show_bug.cgi?id=2536968

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