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Vulnerability · Published Sep 18, 2026 · Assigned by redhat

CVE-2026-93563Io.netty/netty-codec-smtp: netty: unbounded multi-line response accumulation in smtpresponsedecoder leads to memory-exhaustion dos

High 7.5

In plain English

A high-severity security flaw in Red Hat build of Apache Camel for Spring Boot 4 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 26% of all known vulnerabilities).

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.3%top 74.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12nettyno fix listedDEBIAN-CVE-2026-93563
Debian:13nettyno fix listedDEBIAN-CVE-2026-93563
Debian:14nettyno fix listedDEBIAN-CVE-2026-93563
Ubuntu:26.10nettyno fix listedUBUNTU-CVE-2026-93563

Affected products (as reported)

VendorProductVersions
Red Hat Red Hat build of Apache Camel for Spring Boot 4 see references
Red Hat Red Hat Fuse 7 see references
Red Hat Red Hat JBoss Enterprise Application Platform 7 see references
Red Hat Red Hat JBoss Enterprise Application Platform 7 see references
Red Hat Red Hat JBoss Enterprise Application Platform 7 see references
Red Hat Red Hat JBoss Enterprise Application Platform 7 see references
Red Hat Red Hat Single Sign-On 7 see references

Weakness: CWE-1035 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References