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.

Published: 2026-05-18 Last update: 2026-06-08 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-42009 is rated Moderate Risk (47.9/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.78%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-42009

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.71% 0.78% +0.07%
2 2026-06-09 0.49% 0.71% +0.23%
3 2026-06-03 — 0.49% —

Full EPSS history (7 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-42009

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-42009

GitHub Security Advisory for CVE-2026-42009

GHSA-9gx7-g5hv-xjjj · Severity: high — A flaw was found in gnutls. A remote attacker could exploit an issue in the Datagram Transport...

OS Trackers for CVE-2026-42009

vendor priority summary link
debian not yet assigned CVE-2026-42009 not yet assigned priority: Debian including 1 source packages (gnutls28), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2026-42009
suse high — https://www.suse.com/security/cve/CVE-2026-42009/
ubuntu medium CVE-2026-42009 medium priority: Ubuntu including 1 source packages (gnutls28), 8 status rows across 8 suites (bionic, focal, jammy, noble, questing, resolute, upstream, xenial): released 5, needs-triage 3. https://ubuntu.com/security/CVE-2026-42009

Affected software / configurations for CVE-2026-42009

Vendor Product Version Raw CPE
gnu gnutls — cpe:2.3:a:gnu:gnutls:-:*:*:*:*:*:*:*
redhat hardened_images — cpe:2.3:a:redhat:hardened_images:-:*:*:*:*:*:*:*
redhat openshift_container_platform 4.0 cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:*
redhat enterprise_linux 6.0 cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*
redhat enterprise_linux 7.0 cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
redhat enterprise_linux 8.0 cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:arm64:*
redhat enterprise_linux 8.0 cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:x64:*
redhat enterprise_linux_for_els 8.10 cpe:2.3:o:redhat:enterprise_linux_for_els:8.10:*:*:*:*:*:arm64:*
redhat enterprise_linux_for_els 8.10 cpe:2.3:o:redhat:enterprise_linux_for_els:8.10:*:*:*:*:*:x64:*
redhat enterprise_linux_for_ibm_z_systems 8.0_s390x cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems:8.0_s390x:*:*:*:*:*:*:*
redhat enterprise_linux_for_ibm_z_systems_els 8.10 cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems_els:8.10:*:*:*:*:*:*:*
redhat enterprise_linux_for_power_little_endian 8.0_ppc64le cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian:8.0_ppc64le:*:*:*:*:*:*:*
redhat enterprise_linux_for_power_little_endian_els 8.10 cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian_els:8.10:*:*:*:*:*:*:*
redhat enterprise_linux 9.0 cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:arm64:*
redhat enterprise_linux 9.0 cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:x64:*
redhat enterprise_linux 9.8 cpe:2.3:o:redhat:enterprise_linux:9.8:*:*:*:*:*:arm64:*
redhat enterprise_linux_for_els 9.8 cpe:2.3:o:redhat:enterprise_linux_for_els:9.8:*:*:*:*:*:arm64:*
redhat enterprise_linux_for_els 9.8 cpe:2.3:o:redhat:enterprise_linux_for_els:9.8:*:*:*:*:*:x64:*
redhat enterprise_linux_for_eus 9.8 cpe:2.3:o:redhat:enterprise_linux_for_eus:9.8:*:*:*:*:*:arm64:*
redhat enterprise_linux_for_eus 9.8 cpe:2.3:o:redhat:enterprise_linux_for_eus:9.8:*:*:*:*:*:x64:*
redhat enterprise_linux_for_ibm_z_systems 9.0_s390x cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems:9.0_s390x:*:*:*:*:*:*:*
redhat enterprise_linux_for_ibm_z_systems_els 9.8 cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems_els:9.8:*:*:*:*:*:*:*
redhat enterprise_linux_for_ibm_z_systems_eus 9.8 cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems_eus:9.8:*:*:*:*:*:*:*
redhat enterprise_linux_for_power_little_endian 9.0_ppc64le cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian:9.0_ppc64le:*:*:*:*:*:*:*
redhat enterprise_linux_for_power_little_endian_els 9.8 cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian_els:9.8:*:*:*:*:*:*:*
redhat enterprise_linux_for_power_little_endian_eus 9.8 cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian_eus:9.8:*:*:*:*:*:*:*
redhat enterprise_linux_for_update_services_for_sap_solutions 9.8 cpe:2.3:o:redhat:enterprise_linux_for_update_services_for_sap_solutions:9.8:*:*:*:*:*:x64:*
redhat enterprise_linux_server_for_power_little_endian_update_services_for_sap_solutions 9.8 cpe:2.3:o:redhat:enterprise_linux_server_for_power_little_endian_update_services_for_sap_solutions:9.8:*:*:*:*:*:*:*
redhat enterprise_linux 10.0 cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:arm64:*
redhat enterprise_linux 10.0 cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:x64:*
redhat enterprise_linux 10.2 cpe:2.3:o:redhat:enterprise_linux:10.2:*:*:*:*:*:arm64:*
redhat enterprise_linux 10.2 cpe:2.3:o:redhat:enterprise_linux:10.2:*:*:*:*:*:x64:*
redhat enterprise_linux_for_els 10.2 cpe:2.3:o:redhat:enterprise_linux_for_els:10.2:*:*:*:*:*:arm64:*
redhat enterprise_linux_for_els 10.2 cpe:2.3:o:redhat:enterprise_linux_for_els:10.2:*:*:*:*:*:x64:*
redhat enterprise_linux_for_eus 10.2 cpe:2.3:o:redhat:enterprise_linux_for_eus:10.2:*:*:*:*:*:arm64:*
redhat enterprise_linux_for_eus 10.2 cpe:2.3:o:redhat:enterprise_linux_for_eus:10.2:*:*:*:*:*:x64:*
redhat enterprise_linux_for_ibm_z_systems 10.2 cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems:10.2:*:*:*:*:*:*:*
redhat enterprise_linux_for_ibm_z_systems_els 10.2 cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems_els:10.2:*:*:*:*:*:*:*
redhat enterprise_linux_for_ibm_z_systems_eus 10.2 cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems_eus:10.2:*:*:*:*:*:*:*
redhat enterprise_linux_for_power_little_endian 10.0 cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian:10.0:*:*:*:*:*:*:*
redhat enterprise_linux_for_power_little_endian 10.2 cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian:10.2:*:*:*:*:*:*:*
redhat enterprise_linux_for_power_little_endian_els 10.2 cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian_els:10.2:*:*:*:*:*:*:*
redhat enterprise_linux_for_power_little_endian_eus 10.2 cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian_eus:10.2:*:*:*:*:*:*:*

References for CVE-2026-42009

cvelogic Threat Intelligence