CVE-2026-42009

Description

A flaw was found in gnutls. A remote attacker could exploit an issue in the Datagram Transport Layer Security (DTLS) packet reordering logic. The comparator function, responsible for ordering DTLS packets by sequence numbers, did not correctly handle packets with duplicate sequence numbers. This could lead to unstable packet ordering or undefined behavior, resulting in a denial of service.

Overview

State: PUBLISHED
Assigner (CNA): redhat
CVSS severity: HIGH
CVSS score: 7.5 / 10
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Effective score: 7.5 / 10 HIGH source: CNA overview
MSRC score: 7.5 / 10 HIGH MS rating: Moderate
CWE(s): CWE-475
Reserved: 2026-04-23
Published: 2026-05-18 12:44 UTC
Last updated: 2026-05-18 19:05 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/42xxx/CVE-2026-42009.json
Linked Threat: CVE-2026-42009 — Gnutls: gnutls: denial of service via dtls packet reordering vulnerability

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-05-18 13:16:32 UTC
NVD last modified: 2026-05-18 19:32:38 UTC
NVD CVSS v3.1: 7.5 / 10 HIGH source: secalert@redhat.com
NVD CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploitability subscore: 3.9 / 10
Impact subscore: 3.6 / 10
EPSS score: 0.0022 (probability of exploitation in next 30 days)
EPSS percentile: 45.02% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-30769
Assigner: redhat
Published: May 18, 2026, 12:44:45 PM
Updated: May 27, 2026, 2:17:01 AM
EUVD base score (CVSS 3.1): 7.5 / 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EUVD-reported EPSS: 0.2500
Vendors: Red Hat
Products: Red Hat Enterprise Linux 8 (patch: 0:3.6.16-8.el8_10.6)

Red Hat Hardened Images (patch: 3.8.13-1.hum1)
Aliases: GHSA-9gx7-g5hv-xjjj

ENISA description: A flaw was found in gnutls. A remote attacker could exploit an issue in the Datagram Transport Layer Security (DTLS) packet reordering logic. The comparator function, responsible for ordering DTLS packets by sequence numbers, did not correctly handle packets with duplicate sequence numbers. This could lead to unstable packet ordering or undefined behavior, resulting in a denial of service.

EUVD references (4)

Microsoft Security Response Center MSRC

Microsoft's vendor-authoritative record from the Security Update Guide — its own CVSS score, impact, severity rating, exploit assessment, and KB-article fixes. Refreshed 2026-08-15 03:01 UTC (source: CVRF).

MS severity: Moderate
MS CVSS base score: 7.5 / 10 (temporal 6.3)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:R
Release: 2026-May

Microsoft remediations / KB articles (2)

CBL-Mariner Releases — Vendor Fix / Security Update (fixed build 3.8.3-11)
https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade — None Available / CBL-Mariner Releases

Affected products (7)

Vendor	Product	Versions	Platforms
Red Hat	Red Hat Enterprise Linux 10	—	—
Red Hat	Red Hat Enterprise Linux 6	—	—
Red Hat	Red Hat Enterprise Linux 7	—	—
Red Hat	Red Hat Enterprise Linux 8	—	—
Red Hat	Red Hat Enterprise Linux 9	—	—
Red Hat	Red Hat Hardened Images	—	—
Red Hat	Red Hat OpenShift Container Platform 4	—	—

Vendor references (2)

References embedded in the original CVE record by the assigning CNA.

https://access.redhat.com/security/cve/CVE-2026-42009 vdb-entryx_refsource_REDHAT
RHBZ#2467279 issue-trackingx_refsource_REDHAT

Web references (15)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

MSRC update guide: CVE-2026-42009 msrc
None Available msrc
https://access.redhat.com/errata/RHSA-2026:20613 tenable:access.redhat.com
https://access.redhat.com/errata/RHSA-2026:20611 tenable:access.redhat.com
https://access.redhat.com/errata/RHSA-2026:13274 tenable:access.redhat.com
https://access.redhat.com/errata/RHSA-2026:20612 tenable:access.redhat.com
https://attackerkb.com/topics/CVE-2026-42009 rapid7:attackerkb.com
http://cwe.mitre.org/data/definitions/475.html rapid7:cwe.mitre.org
https://security.alpinelinux.org/vuln/CVE-2026-42009 rapid7:security.alpinelinux.org
https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-30769 rapid7:euvd.enisa.europa.eu
https://www.first.org/epss/ tenable:www.first.org
https://access.redhat.com/security/cve/CVE-2026-42009 tenable:access.redhat.com
https://bugzilla.redhat.com/show_bug.cgi?id=2467279 tenable:bugzilla.redhat.com
https://nvd.nist.gov/vuln/detail/CVE-2026-42009 tenable:nvd.nist.gov
https://www.cve.org/CVERecord?id=CVE-2026-42009 tenable:www.cve.org

NVD-tagged references (2)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://access.redhat.com/security/cve/CVE-2026-42009 secalert@redhat.com
https://bugzilla.redhat.com/show_bug.cgi?id=2467279 secalert@redhat.com

Remediations (15)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

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AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-42009.json.

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