High
CVE-2026-42009 — Gnutls: gnutls: denial of service via dtls packet reordering vulnerability
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.
19
Low
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
No exploitation signal in the sources consulted so far.
How the score was calculated
- EPSS 1.1% (30-day exploitation probability)+10
- Technical severity (high)+6
- Automatable exploitation (SSVC)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
1.13%
ahead of 66% of scored CVEs · Oct 14, 2026
Affects
Gnu
Gnutls and 45 more
CVSS base
7.5
High · 4 source(s)
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Exploitation
None
none · proof-of-concept · active
Automatable
Yes
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Gnu Gnutls, Red Hat Cert Manager support for Red Hat OpenShift release 1.17, Red Hat Cert Manager support for Red Hat OpenShift release 1.18…).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes, errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Gnu | Gnutls | versions not specified by the source | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Cert Manager support for Red Hat OpenShift release 1.17 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Cert Manager support for Red Hat OpenShift release 1.18 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Cert Manager support for Red Hat OpenShift release 1.20 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Enterprise Linux | version 7.0version 10.2version 10.0version 9.8version 6.0version 8.0version 9.0 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux For Els | version 10.2version 9.8version 8.10 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux For Eus | version 10.2version 9.8 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux For Ibm Z Systems | version 10.2version 9.0_s390xversion 8.0_s390x | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux For Ibm Z Systems Els | version 8.10version 9.8version 10.2 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux For Ibm Z Systems Eus | version 9.8version 10.2 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux For Power Little Endian | version 8.0_ppc64leversion 10.2version 10.0version 9.0_ppc64le | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux For Power Little Endian Els | version 8.10version 9.8version 10.2 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux For Power Little Endian Eus | version 10.2version 9.8 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux For Update Services For Sap Solutions | version 9.8 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux Server For Power Little Endian Update Services For Sap Solutions | version 9.8 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Hardened Images | versions not specified by the source | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Hardened Images | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Openshift Container Platform | version 4.0 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Red Hat AI Inference Server 3.2 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Discovery 2 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 10 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 10.0 Extended Update Support | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 7 Extended Lifecycle Support | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8.8 Telecommunications Update Service | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 9 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 9.6 Extended Update Support | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift AI 3.4 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.12 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.13 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.14 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.15 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.16 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.17 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.18 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.19 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.20 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.21 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.22 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Update Infrastructure 5 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 7.5 | CVSS 3.1 | High | 3.9 | 3.6 | secalert@redhat.com via NIST National Vulnerability Database |
| 7.5 | CVSS 3.1 | High | 3.9 | 3.6 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c via NIST National Vulnerability Database |
| 7.5 | CVSS 3.1 | High | — | — | GitHub, Inc. via GitHub Security Advisories |
| 7.5 | CVSS 3.1 | High | — | — | redhat via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (score shown at the top: secalert@redhat.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 1.13%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products removed · 1
- Affected products added · red hat/red hat hardened images
- Affected products added · red hat/cert manager support for red hat openshift release 1.17, red hat/cert manager support for red hat openshift rele
- Affected products added · red hat/red hat enterprise linux 10, red hat/red hat enterprise linux 10.0 extended update support, red hat/red hat ente
- SSVC assessment updated
- Record published
- CVSS changed · 7.5
- Source status changed · → Modified
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 3× References added · Oct 14, 2026 – Oct 14, 2026
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
44 on the record
- access.redhat.com/errata/RHSA-2026:56853
- access.redhat.com/errata/RHSA-2026:41921
- access.redhat.com/errata/RHSA-2026:34788
- access.redhat.com/errata/RHSA-2026:20611
- bugzilla.redhat.com/show_bug.cgi
- access.redhat.com/errata/RHSA-2026:36005
- access.redhat.com/errata/RHSA-2026:82372
- access.redhat.com/errata/RHSA-2026:34764
- access.redhat.com/errata/RHSA-2026:60019
- access.redhat.com/errata/RHSA-2026:82304
- access.redhat.com/errata/RHSA-2026:26319
- access.redhat.com/errata/RHSA-2026:58981
- access.redhat.com/errata/RHSA-2026:72502
- access.redhat.com/errata/RHSA-2026:82857
- www.gnutls.org/security-new.html
- access.redhat.com/errata/RHSA-2026:82322
- access.redhat.com/errata/RHSA-2026:40762
- access.redhat.com/errata/RHSA-2026:20613
- access.redhat.com/errata/RHSA-2026:57483
- access.redhat.com/errata/RHSA-2026:13274
- access.redhat.com/errata/RHSA-2026:32962
- nvd.nist.gov/vuln/detail/CVE-2026-42009
- access.redhat.com/errata/RHSA-2026:36006
- access.redhat.com/errata/RHSA-2026:82347
- access.redhat.com/errata/RHSA-2026:56911
- access.redhat.com/errata/RHSA-2026:74674
- access.redhat.com/errata/RHSA-2026:30849
- access.redhat.com/errata/RHSA-2026:34372
- access.redhat.com/errata/RHSA-2026:82888
- access.redhat.com/errata/RHSA-2026:56786
- access.redhat.com/errata/RHSA-2026:59831
- access.redhat.com/errata/RHSA-2026:29197
- access.redhat.com/errata/RHSA-2026:20612
- access.redhat.com/errata/RHSA-2026:30850
- access.redhat.com/errata/RHSA-2026:29794
- github.com/advisories/GHSA-9gx7-g5hv-xjjj
- access.redhat.com/errata/RHSA-2026:30004
- access.redhat.com/errata/RHSA-2026:36004
- access.redhat.com/errata/RHSA-2026:33125
- access.redhat.com/errata/RHSA-2026:82354
- access.redhat.com/security/cve/CVE-2026-42009
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42009.json
- access.redhat.com/errata/RHSA-2026:26409
- access.redhat.com/errata/RHSA-2026:65839
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-110927 Openssh: openssh: a compressed payload can expand past the maximum packet size 6h
- Medium CVE-2026-110924 Openssh: openssh: gssapi delegated credentials can be stored after a failed authentication 6h
- Medium CVE-2026-110925 Openssh: openssh: '$' and '\' in a command-line username expand through %u 14h
- Medium CVE-2026-110923 Openssh: openssh: sftp can write outside the destination directory from a server-supplied path 14h
- Medium CVE-2026-110926 Openssh: openssh: shared lz77 compression dictionary leaks plaintext across channels 14h
- Medium CVE-2026-86847 Dpdk: dpdk: guest can trigger infinite loop in vhost-crypto writeback chain cleanup 1d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-42009 is "Gnutls: gnutls: denial of service via dtls packet reordering vulnerability", rated High. It affects Gnutls (Gnu); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.5 describes technical severity. EPSS 1.13% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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