High severity · published May 18, 2026
CVE-2026-42009
Gnutls: gnutls: denial of service via dtls packet reordering vulnerability
7.5
CVSS
1.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.3% · higher than 71% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CM
Cert Manager support for Red Hat OpenShift release 1.17 · Red Hat
All versions, or not specified · source: vendor
CM
Cert Manager support for Red Hat OpenShift release 1.18 · Red Hat
All versions, or not specified · source: vendor
CM
Cert Manager support for Red Hat OpenShift release 1.20 · Red Hat
All versions, or not specified · source: vendor
RH
Red Hat AI Inference Server 3.2 · Red Hat
All versions, or not specified · source: vendor, CISA
RH
Red Hat Discovery 2 · Red Hat
All versions, or not specified · source: vendor, CISA
RH
Red Hat Enterprise Linux 10 · Red Hat
All versions, or not specified · source: vendor, CISA
RH
Red Hat Enterprise Linux 10.0 Extended Update Support · Red Hat
All versions, or not specified · source: vendor, CISA
RH
Red Hat Enterprise Linux 7 Extended Lifecycle Support · Red Hat
All versions, or not specified · source: vendor, CISA
RH
Red Hat Enterprise Linux 8 · Red Hat
All versions, or not specified · source: vendor, CISA
RH
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support · Red Hat
All versions, or not specified · source: vendor, CISA
RH
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On · Red Hat
All versions, or not specified · source: vendor, CISA
RH
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support · Red Hat
All versions, or not specified · source: vendor, CISA
Affected product
CM
Cert Manager support for Red Hat OpenShift release 1.17
Red Hat
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42009
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-42009
vendor-advisory
https://access.redhat.com/errata/RHSA-2026:13274
vendor-advisory
https://access.redhat.com/errata/RHSA-2026:20611
vendor-advisory
https://access.redhat.com/errata/RHSA-2026:20612
vendor-advisory
https://access.redhat.com/errata/RHSA-2026:20613
vendor-advisory
https://access.redhat.com/errata/RHSA-2026:26319
vendor-advisory
https://access.redhat.com/errata/RHSA-2026:26409
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