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CVE-2026-42010· NVD / CVE Program· CNA redhat

Gnutls: gnutls: authentication bypass via nul character in username

Noroxi assessment

Priority: Monitor (action score 39/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.94% (FIRST EPSS); higher than 60.3% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: gnutls (AlmaLinux:10) 3.8.10-4.el10_2; gnutls-c++ (AlmaLinux:10) 3.8.10-4.el10_2; gnutls-dane (AlmaLinux:10) 3.8.10-4.el10_2.
  • Severity is disputed: the assigning authority (CNA) scores it 7.1, NVD 9.8.

Low priority for now. Upgrade to gnutls (AlmaLinux:10) 3.8.10-4.el10_2; gnutls-c++ (AlmaLinux:10) 3.8.10-4.el10_2; gnutls-dane (AlmaLinux:10) 3.8.10-4.el10_2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
May 7, 2026
Updated
Oct 14, 2026
EPSS
0.9% · 60th percentile

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.9%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
9.8
CNA · redhat
7.1
2.7 point gap

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
gnugnutls
redhathardened images
redhatopenshift container platform
redhatenterprise linux

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Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • gnu gnutlsall versions
  • redhat enterprise linux10.0
  • redhat enterprise linux6.0
  • redhat enterprise linux7.0
  • redhat enterprise linux8.0
  • redhat enterprise linux9.0
  • redhat hardened imagesall versions
  • redhat openshift container platform4.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.

  • gitlab.com/gnutls/gnutls gnutls

    • 0affected

  • Red Hat Cert Manager support for Red Hat OpenShift release 1.17

    • 1791371080 and laternot affected · rpm
    • 1791371069 and laternot affected · rpm
    • 1791788287 and laternot affected · rpm
    • 1791970484 and laternot affected · rpm

  • Red Hat Cert Manager support for Red Hat OpenShift release 1.18

    • 1791459707 and laternot affected · rpm
    • 1791459711 and laternot affected · rpm
    • 1791459759 and laternot affected · rpm
    • 1789029076 and laternot affected · rpm
    • 1791966259 and laternot affected · rpm

  • Red Hat Cert Manager support for Red Hat OpenShift release 1.20

    • 1790598593 and laternot affected · rpm

  • Red Hat Red Hat AI Inference Server 3.2

    • 1782951051 and laternot affected · rpm
    • 1782951012 and laternot affected · rpm
    • 1782951244 and laternot affected · rpm

  • Red Hat Red Hat Discovery 2

    • 1782159791 and laternot affected · rpm
    • 1782166952 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 10

    • 0:3.8.10-4.el10_2 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support

    • 0:3.8.9-9.el10_0.19 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 6

    • all versionsunknown

  • Red Hat Red Hat Enterprise Linux 7

    • all versionsunknown

  • Red Hat Red Hat Enterprise Linux 8

    • 0:3.6.16-8.el8_10.6 and laternot affected · rpm
    • 0:3.6.16-8.el8_10.6 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support

    • 0:3.6.14-10.el8_4.1 and laternot affected · rpm
    • 0:4.13-3.el8_4.1 and laternot affected · rpm

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10gnutlsbefore 3.8.10-4.el10_23.8.10-4.el10_2
AlmaLinux:10gnutls-c++before 3.8.10-4.el10_23.8.10-4.el10_2
AlmaLinux:10gnutls-danebefore 3.8.10-4.el10_23.8.10-4.el10_2
AlmaLinux:10gnutls-develbefore 3.8.10-4.el10_23.8.10-4.el10_2
AlmaLinux:10gnutls-fipsbefore 3.8.10-4.el10_23.8.10-4.el10_2
AlmaLinux:10gnutls-utilsbefore 3.8.10-4.el10_23.8.10-4.el10_2
AlmaLinux:8gnutlsbefore 3.6.16-8.el8_10.63.6.16-8.el8_10.6
AlmaLinux:8gnutls-c++before 3.6.16-8.el8_10.63.6.16-8.el8_10.6
AlmaLinux:8gnutls-danebefore 3.6.16-8.el8_10.63.6.16-8.el8_10.6
AlmaLinux:8gnutls-develbefore 3.6.16-8.el8_10.63.6.16-8.el8_10.6
AlmaLinux:8gnutls-utilsbefore 3.6.16-8.el8_10.63.6.16-8.el8_10.6
AlmaLinux:9gnutlsbefore 3.8.10-4.el9_83.8.10-4.el9_8
AlmaLinux:9gnutls-c++before 3.8.10-4.el9_83.8.10-4.el9_8
AlmaLinux:9gnutls-danebefore 3.8.10-4.el9_83.8.10-4.el9_8
AlmaLinux:9gnutls-develbefore 3.8.10-4.el9_83.8.10-4.el9_8
AlmaLinux:9gnutls-utilsbefore 3.8.10-4.el9_83.8.10-4.el9_8
Alpine:v3.20gnutlsbefore 3.8.13-r03.8.13-r0
Debian:12gnutls28before 3.7.9-2+deb12u73.7.9-2+deb12u7
Debian:13gnutls28before 3.8.9-3+deb13u43.8.9-3+deb13u4
Debian:14gnutls28before 3.8.13-13.8.13-1
openSUSE:Tumbleweedgnutlsbefore 3.8.13-1.13.8.13-1.1
Red Hat:enterprise_linux_eus:10.0gnutlsbefore 0:3.8.9-9.el10_0.190:3.8.9-9.el10_0.19
Red Hat:enterprise_linux_eus:10.0gnutls-c++before 0:3.8.9-9.el10_0.190:3.8.9-9.el10_0.19
Red Hat:enterprise_linux_eus:10.0gnutls-c++-debuginfobefore 0:3.8.9-9.el10_0.190:3.8.9-9.el10_0.19

+96

Same product

gnu: all records

Other highest-scoring records for the same primary product.

  • CVE-2017-5334Double free vulnerability in the gnutls_x509_ext_import_proxy function in GnuTLS before 3.3.26 and 3.5.x before 3.5.8 allows remote attacker
    49Plan
  • CVE-2019-3829A vulnerability was found in gnutls versions from 3.5.8 before 3.6.7.
    48Plan
  • CVE-2008-1948The _gnutls_server_name_recv_params function in lib/ext_server_name.c in libgnutls in gnutls-serv in GnuTLS before 2.2.4 does not properly c
    44Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-3832Apr 30, 2026 · Gnutls: gnutls: security bypass allows acceptance of revoked server certificates via crafted ocsp response
    14Monitor
  • ← EarlierCVE-2026-3833Apr 30, 2026 · Gnutls: gnutls: policy bypass due to case-sensitive nameconstraints comparison
    29Monitor
  • Later →CVE-2026-42009May 18, 2026 · Gnutls: gnutls: denial of service via dtls packet reordering vulnerability
    30Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
almalinux:gnutls3.6.16-8.el8_10.6 · AlmaLinux:8Package registry (OSV)
almalinux:gnutls-c++3.6.16-8.el8_10.6 · AlmaLinux:8Package registry (OSV)
almalinux:gnutls-dane3.6.16-8.el8_10.6 · AlmaLinux:8Package registry (OSV)
almalinux:gnutls-devel3.6.16-8.el8_10.6 · AlmaLinux:8Package registry (OSV)
almalinux:gnutls-fips3.8.10-4.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:gnutls-utils3.6.16-8.el8_10.6 · AlmaLinux:8Package registry (OSV)
alpine:gnutls3.8.13-r0 · Alpine:v3.20Package registry (OSV)
debian:gnutls283.7.9-2+deb12u7 · Debian:12Package registry (OSV)
opensuse:gnutls3.8.13-1.1 · openSUSE:TumbleweedPackage registry (OSV)
red hat:gnutls0:3.8.13-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:gnutls-c++0:3.6.16-8.el8_10.6 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:gnutls-c++0:3.8.13-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:gnutls-c++-debuginfo0:3.6.16-8.el8_10.6 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:gnutls-dane0:3.6.16-8.el8_10.6 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:gnutls-dane0:3.8.13-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:gnutls-dane-debuginfo0:3.6.16-8.el8_10.6 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:gnutls-debuginfo0:3.6.16-8.el8_10.6 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:gnutls-debugsource0:3.6.16-8.el8_10.6 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:gnutls-devel0:3.6.16-8.el8_10.6 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:gnutls-devel0:3.8.13-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:gnutls-fips0:3.8.10-4.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:gnutls-fips0:3.8.13-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:gnutls-utils0:3.6.16-8.el8_10.6 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:gnutls-utils0:3.8.13-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:gnutls-utils-debuginfo0:3.6.16-8.el8_10.6 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:mingw32-gnutls0:3.8.13-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:mingw64-gnutls0:3.8.13-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
rocky linux:gnutls0:3.6.16-8.el8_10.6 · Rocky Linux:8Package registry (OSV)
suse:gnutls3.7.3-150400.24.2 · SUSE:Linux Enterprise Micro 5.3Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-170 · Improper Null Termination

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓
  2. SSVC exploitation— → none

For records you follow, these changes also arrive as notifications. →

References

Show all references (19 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records