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CVE-2026-42009

35
FAUCET Score

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.

First published: May 18, 2026Last modified: Jul 22, 2026

Impacted Technologies

VendorProductVersion(s)CPE
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:gnu:gnutls:-:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:redhat:hardened_images:-:*:*:*:*:*:*:*
4.0CPE matchmatch criteria
cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:*
6.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*
7.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.33%
Probability of exploitation in next 30 days
EPSS Percentile
68.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0134 is in the 48th percentile among its peer group of 51,506 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (11)

microsoftpatch availablevia msrc
Product: 21391-17084Fixed in: 3.8.3-11
microsoftpatch availablevia msrc
Product: 20911-17084Fixed in: 3.8.3-11
microsoftpatch availablevia msrc
Product: azl3 gnutls 3.8.3-11 on Azure Linux 3.0Fixed in: 3.8.3-11
microsoftpatch availablevia msrc
Product: azl3 gnutls 3.8.3-8 on Azure Linux 3.0Fixed in: 3.8.3-11
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (bionic)Fixed in: 3.5.18-1ubuntu1.6+esm3
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (jammy)Fixed in: 3.7.3-4ubuntu1.9
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (xenial)Fixed in: 3.4.10-4ubuntu1.9+esm3
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (focal)Fixed in: 3.6.13-2ubuntu1.12+esm2
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (noble)Fixed in: 3.8.3-1.1ubuntu3.6
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (questing)Fixed in: 3.8.9-3ubuntu2.2
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (resolute)Fixed in: 3.8.12-2ubuntu1.1

Vendor Advisories (3)

ubuntuUSN-8502-1

GnuTLS vulnerabilities

Jul 6, 2026
ubuntuUSN-8284-1

GnuTLS vulnerabilities

May 20, 2026
microsoft2026-May/CVE-2026-42009Moderate

Gnutls: gnutls: denial of service via dtls packet reordering vulnerability

May 12, 2026

References

security.access.redhat.com / data/csaf/v2/vex/2026/cve-2026-42009.json
access.redhat.com / errata/RHSA-2026:13274
Third Party Advisory
access.redhat.com / errata/RHSA-2026:20611
Third Party Advisory
access.redhat.com / errata/RHSA-2026:20612
Third Party Advisory
access.redhat.com / errata/RHSA-2026:20613
Third Party Advisory
access.redhat.com / errata/RHSA-2026:26319
access.redhat.com / errata/RHSA-2026:26409
access.redhat.com / errata/RHSA-2026:29197
access.redhat.com / errata/RHSA-2026:29794
access.redhat.com / errata/RHSA-2026:30004
access.redhat.com / errata/RHSA-2026:30849
access.redhat.com / errata/RHSA-2026:30850
access.redhat.com / errata/RHSA-2026:32962
access.redhat.com / errata/RHSA-2026:33125
access.redhat.com / errata/RHSA-2026:34372
access.redhat.com / errata/RHSA-2026:34764
access.redhat.com / errata/RHSA-2026:34788
access.redhat.com / errata/RHSA-2026:36004
access.redhat.com / errata/RHSA-2026:36005
access.redhat.com / errata/RHSA-2026:36006
access.redhat.com / errata/RHSA-2026:40762
access.redhat.com / errata/RHSA-2026:41921
access.redhat.com / security/cve/CVE-2026-42009
Third Party Advisory
bugzilla.redhat.com / show_bug.cgi
Issue TrackingThird Party Advisory
gnutls.org / security-new.html