Vulnerability-Lookup

UBUNTU-CVE-2026-93563 (CVE-2026-93563)

Vulnerability from osv_ubuntu – Published: 2026-09-18 11:17 – Updated: 2026-09-23 23:40 – Source website

Details

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.

Severity

7.5 (High)


                    
                      CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-93563	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-93563	REPORT
	https://bugzilla.redhat.com/show_bug.cgi?id=2536976	REPORT
	https://github.com/netty/netty/security/advisorie…	REPORT
	https://access.redhat.com/security/cve/CVE-2026-93563	REPORT

JSON

To clipboard

{
  "affected": [
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      "ecosystem_specific": {
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          {
            "binary_name": "libnetty-java",
            "binary_version": "1:3.2.6.Final-2+deb8u2ubuntu0.1~esm1"
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        "name": "netty",
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        "1:4.1.48-9ubuntu0.2",
        "1:4.1.48-9ubuntu0.2+esm1",
        "1:4.1.48-9ubuntu0.2+esm2"
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            "binary_version": "1:4.1.48-16ubuntu0.1~esm2"
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        "1:4.1.48-16",
        "1:4.1.48-16ubuntu0.1~esm2"
      ]
    }
  ],
  "aliases": [],
  "details": "A flaw was found in Netty\u0027s `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\u0027s Java Virtual Machine (JVM) heap, causing an `OutOfMemoryError` and a denial of service (DoS) due to a process crash.",
  "id": "UBUNTU-CVE-2026-93563",
  "modified": "2026-09-23T23:40:09Z",
  "published": "2026-09-18T11:17:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-93563"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-93563"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2536976"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/netty/netty/security/advisories/GHSA-pq4x-537v-r54q"
    },
    {
      "type": "REPORT",
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    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
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      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-93563"
  ]
}

CVE-2026-93563 (GCVE-0-2026-93563)

Vulnerability from cvelistv5 – Published: 2026-09-18 10:58 – Updated: 2026-09-25 08:28

Title

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

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.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-18 19:07 UTC

CWE

CWE-1035

Assigner

redhat redhat root

References

2 references

URL	Tags
https://access.redhat.com/security/cve/CVE-2026-93563	vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2536976	issue-trackingx_refsource_REDHAT

Impacted products

4 products

Vendor	Product	Version
Red Hat	Red Hat build of Apache Camel for Spring Boot 4	cpe:/a:redhat:camel_spring_boot:4
Red Hat	Red Hat Fuse 7	cpe:/a:redhat:jboss_fuse:7
Red Hat	Red Hat JBoss Enterprise Application Platform 7	cpe:/a:redhat:jboss_enterprise_application_platform:7
Red Hat	Red Hat Single Sign-On 7	cpe:/a:redhat:red_hat_single_sign_on:7

Date Public

2026-09-10 00:46

Show details on NVD website

JSON

To clipboard

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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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UBUNTU-CVE-2026-93563 (CVE-2026-93563)

CVE-2026-93563 (GCVE-0-2026-93563)

Tags

Sightings

Nomenclature

Related by attack behaviour