Skip to content
Fencer Vulns
high 7.1

CVE-2026-42010 json

Gnutls: gnutls: authentication bypass via nul character in username

published 2026-05-07 6 mo ago modified 2026-11-04 4 d ago also EUVD-2026-28354

cvss
7.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 64%
public exploits
0
none known

Summary

A flaw was found in gnutls. Servers configured with RSA-PSK (Rivest–Shamir–Adleman – Pre-Shared Key) wrongfully matched usernames containing a NUL character with truncated usernames. A remote attacker could exploit this by sending a specially crafted username, leading to an authentication bypass. This vulnerability allows an attacker to gain unauthorized access by circumventing the authentication process.

Patch / fix

  • Red Hat Red Hat Enterprise Linux 10 0:3.8.10-4.el10_2
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support 0:3.8.9-9.el10_0.19
  • Red Hat Red Hat Enterprise Linux 8 0:3.6.16-8.el8_10.6
  • Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support 0:3.6.14-10.el8_4.1, 0:4.13-3.el8_4.1
  • Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On 0:3.6.14-10.el8_4.1, 0:4.13-3.el8_4.1
  • Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support 0:3.6.16-5.el8_6.5, 0:4.13-3.el8_6.2
  • Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On 0:3.6.16-5.el8_6.5, 0:4.13-3.el8_6.2
  • Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service 0:3.6.16-7.el8_8.4, 0:4.13-4.el8_8.1
  • Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions 0:3.6.16-7.el8_8.4, 0:4.13-4.el8_8.1
  • Red Hat Red Hat Enterprise Linux 9 0:3.8.10-4.el9_8
  • Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 0:3.7.6-21.el9_2.7
  • Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions 0:3.8.3-4.el9_4.6
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support 0:3.8.3-6.el9_6.4
  • Red Hat Red Hat OpenShift Container Platform 4.12 412.86.202608241157-0
  • Red Hat Red Hat OpenShift Container Platform 4.13 413.92.202609080414-0
  • Red Hat Red Hat OpenShift Container Platform 4.14 414.92.202609011250-0
  • Red Hat Red Hat OpenShift Container Platform 4.15 415.92.202609140326-0
  • Red Hat Red Hat OpenShift Container Platform 4.16 416.94.202608150307-0
  • Red Hat Red Hat OpenShift Container Platform 4.17 417.94.202608250221-0
  • Red Hat Red Hat OpenShift Container Platform 4.18 418.94.202608142238-0
  • Red Hat Red Hat OpenShift Container Platform 4.19 4.19.9.6.202607151909-0
  • Red Hat Red Hat OpenShift Container Platform 4.20 4.20.9.6.202607010620-0
  • Red Hat Red Hat OpenShift Container Platform 4.21 4.21.9.6.202607011303-0
  • Red Hat Red Hat OpenShift Container Platform 4.22 4.22.9.8.202606301732-0
  • Red Hat Cert Manager support for Red Hat OpenShift release 1.17 1791371069, 1791371080, 1791788287, 1791970484
  • Red Hat Cert Manager support for Red Hat OpenShift release 1.18 1789029076, 1791459707, 1791459711, 1791459759, 1791966259
  • Red Hat Cert Manager support for Red Hat OpenShift release 1.20 1790598593
  • Red Hat Red Hat AI Inference Server 3.2 1782951012, 1782951051, 1782951244
  • Red Hat Red Hat Discovery 2 1782159791, 1782166952
  • Red Hat Red Hat Hardened Images 3.8.13-1.hum1
  • gnutls28 Debian 12 3.7.9-2+deb12u7
  • gnutls28 Debian 13 3.8.9-3+deb13u4
  • gnutls28 Debian 14 3.8.13-1

debian advisories DEBIAN-CVE-2026-42010

  • gnutls28 Ubuntu 22.04 LTS 3.7.3-4ubuntu1.9
  • gnutls28 Ubuntu 24.04 LTS 3.8.3-1.1ubuntu3.6
  • gnutls28 Ubuntu 25.10 3.8.9-3ubuntu2.2
  • gnutls28 Ubuntu 26.04 LTS 3.8.12-2ubuntu1.1
  • gnutls28 Ubuntu Pro 20.04 LTS 3.6.13-2ubuntu1.12+esm2
  • gnutls28 Ubuntu Pro FIPS-updates 22.04 LTS 3.7.3-4ubuntu1.9+Fips1
  • gnutls28 Ubuntu Pro FIPS-updates 24.04 LTS 3.8.3-1.1ubuntu3.6+Fips1.2

ubuntu advisories UBUNTU-CVE-2026-42010

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • gnutls RHEL 9 3.8.10-4.el9_8
  • gnutls-c++ RHEL 9 3.8.10-4.el9_8
  • gnutls-dane RHEL 9 3.8.10-4.el9_8
  • gnutls-utils RHEL 9 3.8.10-4.el9_8
  • gnutls RHEL 10.2 3.8.10-4.el10_2
  • gnutls-c++ RHEL 10.2 3.8.10-4.el10_2
  • gnutls-dane RHEL 10.2 3.8.10-4.el10_2
  • gnutls-fips RHEL 10.2 3.8.10-4.el10_2

red hat advisories RHSA-2026:41921RHSA-2026:33125RHSA-2026:32962RHSA-2026:30850RHSA-2026:30849RHSA-2026:30004

  • gnutls SLE Micro 5.3 3.7.3-150400.24.2

suse advisories SUSE-SU-2026:2822-1

  • gnutls openSUSE Tumbleweed 3.8.13-1.1

opensuse advisories openSUSE-SU-2026:10691-1

  • gnutls AlmaLinux 8 3.6.16-8.el8_10.6
  • gnutls-c++ AlmaLinux 8 3.6.16-8.el8_10.6
  • gnutls-dane AlmaLinux 8 3.6.16-8.el8_10.6
  • gnutls-utils AlmaLinux 8 3.6.16-8.el8_10.6
  • gnutls AlmaLinux 9 3.8.10-4.el9_8
  • gnutls-c++ AlmaLinux 9 3.8.10-4.el9_8
  • gnutls-dane AlmaLinux 9 3.8.10-4.el9_8
  • gnutls-utils AlmaLinux 9 3.8.10-4.el9_8

almalinux advisories ALSA-2026:20611ALSA-2026:20612ALSA-2026:20613

  • gnutls Rocky Linux 10 3.8.10-4.el10_2
  • gnutls Rocky Linux 9 3.8.10-4.el9_8
  • gnutls Rocky Linux 8 3.6.16-8.el8_10.6

rocky linux advisories RLSA-2026:20613RLSA-2026:20612RLSA-2026:20611

  • gnutls Alpine 3.24, Alpine 3.23, Alpine 3.22 +2 more 3.8.13-r0

alpine advisories ALPINE-CVE-2026-42010

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • gnutls Azure Linux 3.0 3.8.3-11

azure linux advisories AZL-86775

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-42010 updated cvss 7.1

gnutls: gnutls: Authentication Bypass via NUL Character in Username

  • Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available
  • Red Hat Cert Manager support for Red Hat OpenShift release 1.17 cert-manager/cert-manager-operator-rhel9 1791788287, cert-manager/jetstack-cert-manager-rhel9 1791371069, cert-manager/cert-manager-operator-bundle 1791970484, cert-manager/jetstack-cert-manager-acmesolver-rhel9 1791371080
    fixed: vendor fix RHSA-2026:82888
  • Red Hat Cert Manager support for Red Hat OpenShift release 1.18 cert-manager/cert-manager-operator-rhel9 1789029076, cert-manager/jetstack-cert-manager-rhel9 1791459711, cert-manager/cert-manager-istio-csr-rhel9 1791459759, cert-manager/cert-manager-operator-bundle 1791966259, cert-manager/jetstack-cert-manager-acmesolver-rhel9 1791459707
    fixed: vendor fix RHSA-2026:82354
  • Red Hat Cert Manager support for Red Hat OpenShift release 1.20 cert-manager/cert-manager-trust-manager-rhel9 1790598593
    fixed: vendor fix RHSA-2026:72502
  • Red Hat AI Inference Server 3.2 rhaiis/vllm-cuda-rhel9 1782951012, rhaiis/vllm-rocm-rhel9 1782951244, rhaiis/model-opt-cuda-rhel9 1782951051
    fixed: vendor fix RHSA-2026:36004
  • Red Hat Discovery 2 discovery/discovery-ui-rhel9 1782166952, discovery/discovery-server-rhel9 1782159791
    fixed: vendor fix RHSA-2026:29197
  • Red Hat Enterprise Linux AppStream (v. 8) gnutls-c++ 3.6.16-8.el8_10.6, gnutls-dane 3.6.16-8.el8_10.6, gnutls-utils 3.6.16-8.el8_10.6
    fixed: vendor fix RHSA-2026:20611
  • Red Hat Enterprise Linux AppStream (v. 9) gnutls-c++ 3.8.10-4.el9_8, gnutls-dane 3.8.10-4.el9_8, gnutls-utils 3.8.10-4.el9_8
    fixed: vendor fix RHSA-2026:20612
show 32 more
  • Red Hat Enterprise Linux AppStream (v. 10) gnutls-c++ 3.8.10-4.el10_2, gnutls-dane 3.8.10-4.el10_2, gnutls-fips 3.8.10-4.el10_2, gnutls-utils 3.8.10-4.el10_2
    fixed: vendor fix RHSA-2026:20613
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) gnutls-c++ 3.6.14-10.el8_4.1, gnutls-dane 3.6.14-10.el8_4.1, libtasn1-tools 4.13-3.el8_4.1, gnutls-utils 3.6.14-10.el8_4.1
    fixed: vendor fix RHSA-2026:33125
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) gnutls-c++ 3.6.16-5.el8_6.5, gnutls-dane 3.6.16-5.el8_6.5, gnutls-utils 3.6.16-5.el8_6.5, libtasn1-tools 4.13-3.el8_6.2
    fixed: vendor fix RHSA-2026:30849
  • Red Hat Enterprise Linux AppStream E4S (v.8.8) gnutls-c++ 3.6.16-7.el8_8.4, gnutls-dane 3.6.16-7.el8_8.4, gnutls-utils 3.6.16-7.el8_8.4, libtasn1-tools 4.13-4.el8_8.1
    fixed: vendor fix RHSA-2026:30850
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) gnutls-c++ 3.7.6-21.el9_2.7, gnutls-dane 3.7.6-21.el9_2.7, gnutls-utils 3.7.6-21.el9_2.7
    fixed: vendor fix RHSA-2026:41921
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) gnutls-c++ 3.8.3-4.el9_4.6, gnutls-dane 3.8.3-4.el9_4.6, gnutls-utils 3.8.3-4.el9_4.6
    fixed: vendor fix RHSA-2026:32962
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) gnutls-c++ 3.8.9-9.el10_0.19, gnutls-dane 3.8.9-9.el10_0.19, gnutls-fips 3.8.9-9.el10_0.19, gnutls-utils 3.8.9-9.el10_0.19
    fixed: vendor fix RHSA-2026:26409
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) gnutls-c++ 3.8.3-6.el9_6.4, gnutls-dane 3.8.3-6.el9_6.4, gnutls-utils 3.8.3-6.el9_6.4
    fixed: vendor fix RHSA-2026:30004
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) gnutls-c++ 3.6.14-10.el8_4.1, gnutls-dane 3.6.14-10.el8_4.1, libtasn1-tools 4.13-3.el8_4.1, gnutls-utils 3.6.14-10.el8_4.1
    fixed: vendor fix RHSA-2026:33125
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) gnutls-c++ 3.6.16-5.el8_6.5, gnutls-dane 3.6.16-5.el8_6.5, gnutls-utils 3.6.16-5.el8_6.5, libtasn1-tools 4.13-3.el8_6.2
    fixed: vendor fix RHSA-2026:30849
  • Red Hat Enterprise Linux AppStream TUS (v.8.8) gnutls-c++ 3.6.16-7.el8_8.4, gnutls-dane 3.6.16-7.el8_8.4, gnutls-utils 3.6.16-7.el8_8.4, libtasn1-tools 4.13-4.el8_8.1
    fixed: vendor fix RHSA-2026:30850
  • Red Hat Enterprise Linux BaseOS (v. 8) gnutls 3.6.16-8.el8_10.6
    fixed: vendor fix RHSA-2026:20611
  • Red Hat Enterprise Linux BaseOS (v. 9) gnutls 3.8.10-4.el9_8
    fixed: vendor fix RHSA-2026:20612
  • Red Hat Enterprise Linux BaseOS (v. 10) gnutls 3.8.10-4.el10_2
    fixed: vendor fix RHSA-2026:20613
  • Red Hat Enterprise Linux BaseOS AUS (v.8.4) libtasn1 4.13-3.el8_4.1, gnutls 3.6.14-10.el8_4.1
    fixed: vendor fix RHSA-2026:33125
  • Red Hat Enterprise Linux BaseOS AUS (v.8.6) gnutls 3.6.16-5.el8_6.5, libtasn1 4.13-3.el8_6.2
    fixed: vendor fix RHSA-2026:30849
  • Red Hat Enterprise Linux BaseOS E4S (v.8.8) gnutls 3.6.16-7.el8_8.4, libtasn1 4.13-4.el8_8.1
    fixed: vendor fix RHSA-2026:30850
  • Red Hat Enterprise Linux BaseOS E4S (v.9.2) gnutls 3.7.6-21.el9_2.7
    fixed: vendor fix RHSA-2026:41921
  • Red Hat Enterprise Linux BaseOS E4S (v.9.4) gnutls 3.8.3-4.el9_4.6
    fixed: vendor fix RHSA-2026:32962
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) gnutls 3.8.9-9.el10_0.19
    fixed: vendor fix RHSA-2026:26409
  • Red Hat Enterprise Linux BaseOS EUS (v.9.6) gnutls 3.8.3-6.el9_6.4
    fixed: vendor fix RHSA-2026:30004
  • Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4) libtasn1 4.13-3.el8_4.1, gnutls 3.6.14-10.el8_4.1
    fixed: vendor fix RHSA-2026:33125
  • Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.6) gnutls 3.6.16-5.el8_6.5, libtasn1 4.13-3.el8_6.2
    fixed: vendor fix RHSA-2026:30849
  • Red Hat Enterprise Linux BaseOS TUS (v.8.8) gnutls 3.6.16-7.el8_8.4, libtasn1 4.13-4.el8_8.1
    fixed: vendor fix RHSA-2026:30850
  • Red Hat Hardened Images gnutls 3.8.13-1.hum1, gnutls-c++ 3.8.13-1.hum1, gnutls-dane 3.8.13-1.hum1, gnutls-fips 3.8.13-1.hum1, gnutls-utils 3.8.13-1.hum1, mingw32-gnutls 3.8.13-1.hum1, +1 more
    fixed: vendor fix RHSA-2026:13274
  • Red Hat OpenShift AI 3.4 rhai/base-image-neuron-rhel9 1790703542
    fixed: vendor fix RHSA-2026:74674
  • Red Hat OpenShift Container Platform 4.12 rhcos 412.86.202608241157
    fixed: vendor fix RHSA-2026:59831
  • Red Hat OpenShift Container Platform 4.13 rhcos 413.92.202609080414
    fixed: vendor fix RHSA-2026:65839
  • Red Hat OpenShift Container Platform 4.14 rhcos 414.92.202609011250
    fixed: vendor fix RHSA-2026:62409
  • Red Hat OpenShift Container Platform 4.15 rhcos 415.92.202609140326
    fixed: vendor fix RHSA-2026:67857
  • Red Hat OpenShift Container Platform 4.16 rhcos 416.94.202608150307
    fixed: vendor fix RHSA-2026:56853
  • Red Hat OpenShift Container Platform 4.17 rhcos 417.94.202608250221
    fixed: vendor fix RHSA-2026:60019

6 more fixed, 20 more not affected in the full advisory

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
6 mo ago

Exploit prediction

1.05% chance of exploitation in the next 30 days, higher than 64% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
CISA ADP 3.1 7.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
  • Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
  • Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
  • Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
  • Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service
  • Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support
  • Red Hat Red Hat OpenShift Container Platform 4.12
  • Red Hat Red Hat OpenShift Container Platform 4.13
  • Red Hat Red Hat OpenShift Container Platform 4.14
  • Red Hat Red Hat OpenShift Container Platform 4.15
  • Red Hat Red Hat OpenShift Container Platform 4.16
  • Red Hat Red Hat OpenShift Container Platform 4.17
  • Red Hat Red Hat OpenShift Container Platform 4.18
  • Red Hat Red Hat OpenShift Container Platform 4.19
  • Red Hat Red Hat OpenShift Container Platform 4.20
  • Red Hat Red Hat OpenShift Container Platform 4.21
  • Red Hat Red Hat OpenShift Container Platform 4.22
  • Red Hat Cert Manager support for Red Hat OpenShift release 1.17
  • Red Hat Cert Manager support for Red Hat OpenShift release 1.18
  • Red Hat Cert Manager support for Red Hat OpenShift release 1.20
  • Red Hat Red Hat AI Inference Server 3.2
  • Red Hat Red Hat Discovery 2
  • Red Hat Red Hat Hardened Images
  • Red Hat Red Hat OpenShift AI 3.4
  • Red Hat Red Hat Update Infrastructure 5
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat OpenShift Container Platform 4
  • Red Hat Red Hat OpenShift Container Platform 5

Classification

Weakness
  • CWE-170 Improper Null Termination
  • CWE-626 Null Byte Interaction Error (Poison Null Byte)

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.