CVE-2026-42009

MEDIUM

7.5

CVSS v3

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.

CWE-475

How to fix

Remediation Available

gnutls28Debian

Fixed in:3.7.1-5+deb11u10CVE-2026-42009

Fixed in:3.7.9-2+deb12u7CVE-2026-42009

Fixed in:3.8.9-3+deb13u4CVE-2026-42009

Fixed in:3.8.13-1CVE-2026-42009

gnutlsRed Hat / RHEL

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

gnutlsRocky

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

gnutls-c++Red Hat / RHEL

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

gnutls-c++Rocky

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

gnutls-c++-debuginfoRed Hat / RHEL

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

gnutls-c++-debuginfoRocky

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

gnutls-daneRocky

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

gnutls-daneRed Hat / RHEL

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

gnutls-dane-debuginfoRocky

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

gnutls-dane-debuginfoRed Hat / RHEL

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

gnutls-debuginfoRed Hat / RHEL

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

gnutls-debuginfoRocky

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

gnutls-debugsourceRed Hat / RHEL

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

gnutls-debugsourceRocky

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

gnutls-develRocky

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

gnutls-develRed Hat / RHEL

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

gnutls-fipsRocky

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

gnutls-fipsRed Hat / RHEL

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

gnutls-utilsRed Hat / RHEL

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

gnutls-utilsRocky

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

gnutls-utils-debuginfoRed Hat / RHEL

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

gnutls-utils-debuginfoRocky

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

Fixed in:0:3.8.9-9.el10_0.19RHSA-2026:26409

Fixed in:0:3.8.10-4.el10_2RHSA-2026:20613

libtasn1Red Hat / RHEL

Fixed in:0:4.13-3.el8_6.2RHSA-2026:30849

Fixed in:0:4.13-3.el8_4.1RHSA-2026:33125

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

Fixed in:0:4.13-3.el8_6.2RHSA-2026:30849

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

Fixed in:0:4.13-3.el8_4.1RHSA-2026:33125

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

libtasn1Rocky

Fixed in:0:4.13-3.el8_6.2RHSA-2026:30849

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

Fixed in:0:4.13-3.el8_4.1RHSA-2026:33125

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

Fixed in:0:4.13-3.el8_6.2RHSA-2026:30849

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

Fixed in:0:4.13-3.el8_6.2RHSA-2026:30849

libtasn1-debuginfoRocky

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

Fixed in:0:4.13-3.el8_4.1RHSA-2026:33125

Fixed in:0:4.13-3.el8_6.2RHSA-2026:30849

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

Fixed in:0:4.13-3.el8_4.1RHSA-2026:33125

Fixed in:0:4.13-3.el8_6.2RHSA-2026:30849

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

libtasn1-debuginfoRed Hat / RHEL

Fixed in:0:4.13-3.el8_6.2RHSA-2026:30849

Fixed in:0:4.13-3.el8_4.1RHSA-2026:33125

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

Fixed in:0:4.13-3.el8_6.2RHSA-2026:30849

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

libtasn1-debugsourceRocky

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

Fixed in:0:4.13-3.el8_6.2RHSA-2026:30849

Fixed in:0:4.13-3.el8_4.1RHSA-2026:33125

Fixed in:0:4.13-3.el8_6.2RHSA-2026:30849

Fixed in:0:4.13-3.el8_4.1RHSA-2026:33125

libtasn1-debugsourceRed Hat / RHEL

Fixed in:0:4.13-3.el8_6.2RHSA-2026:30849

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

Fixed in:0:4.13-3.el8_6.2RHSA-2026:30849

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

Fixed in:0:4.13-3.el8_4.1RHSA-2026:33125

libtasn1-develRocky

Fixed in:0:4.13-3.el8_4.1RHSA-2026:33125

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

Fixed in:0:4.13-3.el8_4.1RHSA-2026:33125

Fixed in:0:4.13-4.el8_8.1RHSA-2026:30850

Fixed in:0:4.13-3.el8_6.2RHSA-2026:30849

This vulnerability affects an unusually large number of packages. The highest-confidence fixes are shown above; the full list is longer. Check the referenced advisories for complete coverage.

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:R

Exploit Intelligence

1.33%probability of exploitation in 30 days

69thpercentile

Moderate risk: more likely to be exploited than 69% of all known CVEs.

References

Related Vulnerabilities

Other CWE-475 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-7925	High	7.5	1.7%	-	Fix
CVE-2025-47865	High	7.5	1.6%	-	-
CVE-2024-20380	High	7.5	1.1%	-	-
CVE-2023-2253	Medium	6.5	0.9%	-	Fix
CVE-2023-4874	Medium	4.3	0.7%	-	Fix
CVE-2024-10569	High	7.5	0.6%	-	-

Common questions

How do I fix CVE-2026-42009?

Published advisories record a fix for 69 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Is CVE-2026-42009 being actively exploited?

Not that we know of. CVE-2026-42009 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 1.3% is the estimated probability that it will be exploited in the next 30 days. That is higher than 69% of all scored CVEs.

How severe is CVE-2026-42009?

CVE-2026-42009 has a CVSS v3 base score of 7.5, rated moderate. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-42009 affect?

Published advisories record a fix for gnutls28 (Debian), gnutls (Red Hat / RHEL), gnutls (Rocky), gnutls-c++ (Red Hat / RHEL), and 65 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

Embed a live status badge for CVE-2026-42009

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-27.