{"document":{"aggregate_severity":{"namespace":"https://access.redhat.com/security/updates/classification/","text":"Important"},"category":"csaf_vex","csaf_version":"2.0","distribution":{"text":"Copyright © Red Hat, Inc. All rights reserved.","tlp":{"label":"WHITE","url":"https://www.first.org/tlp/"}},"lang":"en","notes":[{"category":"legal_disclaimer","text":"This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original.","title":"Terms of Use"}],"publisher":{"category":"vendor","contact_details":"https://access.redhat.com/security/team/contact/","issuing_authority":"Red Hat Product Security is responsible for vulnerability handling across all Red Hat products and services.","name":"Red Hat Product Security","namespace":"https://www.redhat.com"},"references":[{"category":"self","summary":"Canonical URL","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-93563.json"}],"title":"io.netty/netty-codec-smtp: Netty: Unbounded multi-line response accumulation in SmtpResponseDecoder leads to memory-exhaustion DoS","tracking":{"current_release_date":"2026-09-18T23:15:10+00:00","generator":{"date":"2026-09-18T23:15:10+00:00","engine":{"name":"Red Hat 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7","product_id":"red_hat_single_sign-on_7:netty-codec-smtp"},"product_reference":"netty-codec-smtp","relates_to_product_reference":"red_hat_single_sign-on_7"}]},"vulnerabilities":[{"cve":"CVE-2026-93563","cwe":{"id":"CWE-1035","name":"CWE-1035"},"discovery_date":"2026-09-10T00:46:23+00:00","ids":[{"system_name":"Red Hat Bugzilla ID","text":"2536976"}],"notes":[{"category":"description","text":"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.","title":"Vulnerability description"},{"category":"summary","text":"io.netty/netty-codec-smtp: Netty: Unbounded multi-line response accumulation in SmtpResponseDecoder leads to memory-exhaustion DoS","title":"Vulnerability summary"},{"category":"other","text":"Important: Netty's `SmtpResponseDecoder` is vulnerable to a denial of service due to unbounded memory accumulation when processing multi-line SMTP responses. An attacker controlling an SMTP server or performing a Man-in-the-Middle attack can exploit this to exhaust client-side memory, leading to application crashes and total availability loss for affected SMTP client/MTA processes.","title":"Statement"},{"category":"general","text":"The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.","title":"CVSS score applicability"}],"product_status":{"known_affected":["red_hat_build_of_apache_camel_for_spring_boot_4:netty-codec-smtp","red_hat_fuse_7:netty-codec-smtp","red_hat_jboss_enterprise_application_platform_7:jboss-eap-7/eap74-els-openjdk11-openshift-rhel8","red_hat_jboss_enterprise_application_platform_7:jboss-eap-7/eap74-els-openjdk17-openshift-rhel8","red_hat_jboss_enterprise_application_platform_7:jboss-eap-7/eap74-els-openjdk8-openshift-rhel8","red_hat_jboss_enterprise_application_platform_7:netty-codec-smtp","red_hat_single_sign-on_7:netty-codec-smtp"]},"references":[{"category":"self","summary":"Canonical URL","url":"https://access.redhat.com/security/cve/CVE-2026-93563"},{"category":"external","summary":"RHBZ#2536976","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2536976"},{"category":"external","summary":"https://www.cve.org/CVERecord?id=CVE-2026-93563","url":"https://www.cve.org/CVERecord?id=CVE-2026-93563"},{"category":"external","summary":"https://nvd.nist.gov/vuln/detail/CVE-2026-93563","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93563"}],"release_date":"2026-09-10T00:46:23+00:00","remediations":[{"category":"workaround","details":"See https://github.com/netty/netty/security/advisories/GHSA-pq4x-537v-r54q for fixed versions and remediation guidance.","product_ids":["red_hat_build_of_apache_camel_for_spring_boot_4:netty-codec-smtp","red_hat_fuse_7:netty-codec-smtp","red_hat_jboss_enterprise_application_platform_7:jboss-eap-7/eap74-els-openjdk11-openshift-rhel8","red_hat_jboss_enterprise_application_platform_7:jboss-eap-7/eap74-els-openjdk17-openshift-rhel8","red_hat_jboss_enterprise_application_platform_7:jboss-eap-7/eap74-els-openjdk8-openshift-rhel8","red_hat_jboss_enterprise_application_platform_7:netty-codec-smtp","red_hat_single_sign-on_7:netty-codec-smtp"]},{"category":"no_fix_planned","details":"Will not fix","product_ids":["red_hat_jboss_enterprise_application_platform_7:jboss-eap-7/eap74-els-openjdk11-openshift-rhel8","red_hat_jboss_enterprise_application_platform_7:jboss-eap-7/eap74-els-openjdk17-openshift-rhel8","red_hat_jboss_enterprise_application_platform_7:jboss-eap-7/eap74-els-openjdk8-openshift-rhel8","red_hat_jboss_enterprise_application_platform_7:netty-codec-smtp"]},{"category":"none_available","details":"Affected","product_ids":["red_hat_build_of_apache_camel_for_spring_boot_4:netty-codec-smtp","red_hat_fuse_7:netty-codec-smtp","red_hat_single_sign-on_7:netty-codec-smtp"]}],"scores":[{"cvss_v3":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"products":["red_hat_build_of_apache_camel_for_spring_boot_4:netty-codec-smtp","red_hat_fuse_7:netty-codec-smtp","red_hat_jboss_enterprise_application_platform_7:jboss-eap-7/eap74-els-openjdk11-openshift-rhel8","red_hat_jboss_enterprise_application_platform_7:jboss-eap-7/eap74-els-openjdk17-openshift-rhel8","red_hat_jboss_enterprise_application_platform_7:jboss-eap-7/eap74-els-openjdk8-openshift-rhel8","red_hat_jboss_enterprise_application_platform_7:netty-codec-smtp","red_hat_single_sign-on_7:netty-codec-smtp"]}],"threats":[{"category":"impact","details":"Important","product_ids":["red_hat_build_of_apache_camel_for_spring_boot_4:netty-codec-smtp","red_hat_fuse_7:netty-codec-smtp","red_hat_jboss_enterprise_application_platform_7:jboss-eap-7/eap74-els-openjdk11-openshift-rhel8","red_hat_jboss_enterprise_application_platform_7:jboss-eap-7/eap74-els-openjdk17-openshift-rhel8","red_hat_jboss_enterprise_application_platform_7:jboss-eap-7/eap74-els-openjdk8-openshift-rhel8","red_hat_jboss_enterprise_application_platform_7:netty-codec-smtp","red_hat_single_sign-on_7:netty-codec-smtp"]}],"title":"io.netty/netty-codec-smtp: Netty: Unbounded multi-line response accumulation in SmtpResponseDecoder leads to memory-exhaustion DoS"}]}