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.
Published: 2026-09-18
Score: 7.5 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

Vendor Workaround

See https://github.com/netty/netty/security/advisories/GHSA-pq4x-537v-r54q for fixed versions and remediation guidance.

Tracking

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Advisories

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History

Sat, 19 Sep 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Important


Fri, 18 Sep 2026 21:30:00 +0000

Type Values Removed Values Added
Description Unbounded multi-line response accumulation in SmtpResponseDecoder leads to memory-exhaustion DoS 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.
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 18 Sep 2026 13:45:00 +0000

Type Values Removed Values Added
Title Netty: netty-codec-smtp: io.netty/netty-codec-smtp: netty: unbounded multi-line response accumulation in smtpresponsedecoder leads to memory-exhaustion dos Io.netty/netty-codec-smtp: netty: unbounded multi-line response accumulation in smtpresponsedecoder leads to memory-exhaustion dos

Fri, 18 Sep 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Fri, 18 Sep 2026 11:00:00 +0000

Type Values Removed Values Added
Description Unbounded multi-line response accumulation in SmtpResponseDecoder leads to memory-exhaustion DoS
Title Netty: netty-codec-smtp: io.netty/netty-codec-smtp: netty: unbounded multi-line response accumulation in smtpresponsedecoder leads to memory-exhaustion dos
First Time appeared Redhat
Redhat camel Spring Boot
Redhat jboss Enterprise Application Platform
Redhat jboss Fuse
Redhat red Hat Single Sign On
Weaknesses CWE-1035
CPEs cpe:/a:redhat:camel_spring_boot:4
cpe:/a:redhat:jboss_enterprise_application_platform:7
cpe:/a:redhat:jboss_fuse:7
cpe:/a:redhat:red_hat_single_sign_on:7
Vendors & Products Redhat
Redhat camel Spring Boot
Redhat jboss Enterprise Application Platform
Redhat jboss Fuse
Redhat red Hat Single Sign On
References

Subscriptions

Redhat Camel Spring Boot Jboss Enterprise Application Platform Jboss Fuse Red Hat Single Sign On
cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-09-18T20:11:58.092Z

Reserved: 2026-09-18T09:56:54.043Z

Link: CVE-2026-93563

cve-icon Vulnrichment

Updated: 2026-09-18T19:07:49.243Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-09-18T11:17:21.773

Modified: 2026-09-18T21:18:47.130

Link: CVE-2026-93563

cve-icon Redhat

Severity : Important

Publid Date: 2026-09-10T00:46:23Z

Links: CVE-2026-93563 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-09-19T00:30:16Z

Weaknesses