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Fencer Vulns
high 7.5

CVE-2026-93563 json

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

published 2026-09-18 51 d ago modified 2026-09-25 44 d ago also EUVD-2026-82873

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 25%
public exploits
0
none known

Summary

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.

Patch / fix

  • netty-tcnative SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 2.0.84-150200.3.51.1
  • netty SLE Module for Package Hub 15 SP7 4.1.138-150200.4.56.1

suse advisories SUSE-SU-2026:4391-1

  • netty openSUSE Tumbleweed 4.1.138-1.1

opensuse advisories openSUSE-SU-2026:11882-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-93563 updated cvss 7.5

io.netty/netty-codec-smtp: Netty: Unbounded multi-line response accumulation in SmtpResponseDecoder leads to memory-exhaustion DoS

  • Red Hat build of Apache Camel for Spring Boot 4 netty-codec-smtp 4.1.136.Final-redhat-00001
    affected: workaround, no fix available “See https://github.com/netty/netty/security/advisories/GHSA-pq4x-537v-r54q for fixed versions and remediation guidance.”
  • Red Hat JBoss Enterprise Application Platform 7 netty-codec-smtp 4.1.136.Final-redhat-00001, jboss-eap-7/eap74-els-openjdk8-openshift-rhel8, jboss-eap-7/eap74-els-openjdk11-openshift-rhel8, jboss-eap-7/eap74-els-openjdk17-openshift-rhel8 Red Hat Single Sign-On 7 netty-codec-smtp 4.1.136.Final-redhat-00001
    affected: workaround, no fix planned “See https://github.com/netty/netty/security/advisories/GHSA-pq4x-537v-r54q for fixed versions and remediation guidance.”
  • Red Hat Fuse 7 netty-codec-smtp 4.1.136.Final-redhat-00001
    not affected: vulnerable code not in execute path

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
51 d ago

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 25% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

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

Classification

Weakness
  • CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.