CVE-2026-93563 Affecting netty-codec-smtp package, versions *


Severity

Recommended
0.0
high
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.33% (24th percentile)

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  • Snyk IDSNYK-RHEL9-NETTYCODECSMTP-20044929
  • published22 Sept 2026
  • disclosed10 Sept 2026

Introduced: 10 Sep 2026

CVE-2026-93563  (opens in a new tab)
CWE-1035  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:9 netty-codec-smtp.

NVD Description

Note: Versions mentioned in the description apply only to the upstream netty-codec-smtp package and not the netty-codec-smtp package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

A flaw was found in Netty's SmtpResponseDecoder component. A remote attacker, acting as a malicious or man-in-the-middle (MITM) SMTP server, could exploit this by sending a specially crafted, unbounded multi-line SMTP response without a terminator. This vulnerability leads to unbounded memory accumulation within the client's Java Virtual Machine (JVM) heap, causing an OutOfMemoryError and a denial of service (DoS) due to a process crash.

CVSS Base Scores

version 3.1