Vulnerability in GNU Gnutls
CVE-2026-42009
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 · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.011 (65.8th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 66th percentile — 65.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.013 · newest: 0.011 · change: -0.002
Affected products
- GNU Gnutls
- Red Hat Ai Inference Server 3.2 — versions 1782951051, 1782951244, 1782951012
- Red Hat Discovery 2 — versions 1782159791, 1782166952
- Red Hat Enterprise Linux 10 — versions 0:3.8.10-4.el10_2
- Red Hat Enterprise Linux 10.0 Extended Update Support — versions 0:3.8.9-9.el10_0.19
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 7 Extended Lifecycle Support — versions 0:3.3.29-9.el7_9.1
- Red Hat Enterprise Linux 8 — versions 0:3.6.16-8.el8_10.6
- Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support — versions 0:3.6.14-10.el8_4.1, 0:4.13-3.el8_4.1
Weakness classification (CWE)
References
- access.redhat.com/security/cve/CVE-2026-42009 (Third Party Advisory, vdb-entry)
- bugzilla.redhat.com/show_bug.cgi (issue-tracking, Third Party Advisory, Issue Tracking)
- access.redhat.com/errata/RHSA-2026:13274 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2026:20611 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2026:20613 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2026:20612 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2026:26319 (vendor-advisory)
- access.redhat.com/errata/RHSA-2026:26409 (vendor-advisory)
- access.redhat.com/errata/RHSA-2026:29197 (vendor-advisory)
- www.gnutls.org/security-new.html
Frequently asked questions
- What is CVE-2026-42009?
- CVE-2026-42009 is a high-severity vulnerability in GNU Gnutls, classified under CWE-475. CVSS score: 7.5/10. Published 2026-05-18.
- How severe is CVE-2026-42009?
- High severity. CVSS v3 base score is 7.5 out of 10.