7.5

CVE-2026-42009: gnu gnutls Undefined Behavior for Input to API

CVSS: 7.5v3.1HighModified
AliasesALPINE-CVE-2026-42009UBUNTU-CVE-2026-42009DEBIAN-CVE-2026-42009
Published 18-05-2026Last modified 14-10-2026
Open JSON

Vulnerability summary

CVE-2026-42009 is a high (CVSS 7.5) Undefined Behavior for Input to API vulnerability in gnu gnutls. EPSS estimates a 1.13% chance of exploitation in the next 30 days, higher than 65.8% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
1.13%
0%100%
Low · -0.21 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 17 · Related 6
OPENSUSE-SU-2026:10691-1RHSA-2026:13274RHSA-2026:20611RHSA-2026:20612RHSA-2026:20613RHSA-2026:26409

Timeline

  1. 18-05-2026
    PublishedVulnerability first disclosed.
  2. 14-10-2026
    Last modifiedVulnerability information updated.

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 metrics

5 scores · 5 sources · 1 version

EPSS trend

Probability

1.13%

Chance of exploitation in the next 30 days

Percentile

66%

Versus all other CVEs

30-day change

-0.21 pp

From 1.33% on 18-09-2026

18-09-202618-10-2026
EPSS score
1.13%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Redhat13 products
Alpine1 product
  • gnutls< 3.8.13-r0
Debian1 product
  • gnutls28< 3.7.9-2+deb12u7 | < 3.8.9-3+deb13u4 | < 3.8.13-1
Gnu1 product
Ubuntu1 product
  • gnutls28< 3.4.10-4ubuntu1.9+esm3 | < 3.5.18-1ubuntu1.6+esm3 | < 3.6.13-2ubuntu1.12+esm2 | < 3.7.3-4ubuntu1.9 | All versions (No fix recorded) | < 3.7.3-4ubuntu1.9+Fips1 | < 3.8.3-1.1ubuntu3.6 | < 3.8.3-1.1ubuntu3.6+Fips1.2 | < 3.8.9-3ubuntu2.2 | < 3.8.12-2ubuntu1.1

5 vendors · 17 products

References

49 links
Show all 49 references