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CVE-2026-42010

42
FAUCET Score

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.

First published: May 7, 2026Last modified: Jul 22, 2026

Impacted Technologies

VendorProductVersion(s)CPE
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:gnu:gnutls:-:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:redhat:hardened_images:-:*:*:*:*:*:*:*
4.0CPE matchmatch criteria
cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:*
6.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*
7.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.1HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
4.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.05%
Probability of exploitation in next 30 days
EPSS Percentile
60.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0105 is in the 46th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (12)

microsoftpatch availablevia msrc
Product: 21391-17084Fixed in: 3.8.3-11
microsoftpatch availablevia msrc
Product: azl3 gnutls 3.8.3-8 on Azure Linux 3.0Fixed in: 3.8.3-10
microsoftpatch availablevia msrc
Product: azl3 gnutls 3.8.3-11 on Azure Linux 3.0Fixed in: 3.8.3-11
microsoftpatch availablevia msrc
Product: 20911-17084Fixed in: 3.8.3-10
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (questing)Fixed in: 3.8.9-3ubuntu2.2
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (focal)Fixed in: 3.6.13-2ubuntu1.12+esm2
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (xenial)Fixed in: 3.4.10-4ubuntu1.9+esm3
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (resolute)Fixed in: 3.8.12-2ubuntu1.1
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (bionic)Fixed in: 3.5.18-1ubuntu1.6+esm3
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (jammy)Fixed in: 3.7.3-4ubuntu1.9
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (noble)Fixed in: 3.8.3-1.1ubuntu3.6
redhatvendor investigatingvia nvd_reference
View patch

Vendor Advisories (3)

ubuntuUSN-8502-1

GnuTLS vulnerabilities

Jul 6, 2026
ubuntuUSN-8284-1

GnuTLS vulnerabilities

May 20, 2026
microsoft2026-May/CVE-2026-42010Moderate

Gnutls: gnutls: authentication bypass via nul character in username

May 12, 2026

References

security.access.redhat.com / data/csaf/v2/vex/2026/cve-2026-42010.json
access.redhat.com / errata/RHSA-2026:13274
access.redhat.com / errata/RHSA-2026:20611
access.redhat.com / errata/RHSA-2026:20612
access.redhat.com / errata/RHSA-2026:20613
access.redhat.com / errata/RHSA-2026:26319
access.redhat.com / errata/RHSA-2026:26409
access.redhat.com / errata/RHSA-2026:29197
access.redhat.com / errata/RHSA-2026:30004
access.redhat.com / errata/RHSA-2026:30849
access.redhat.com / errata/RHSA-2026:30850
access.redhat.com / errata/RHSA-2026:32962
access.redhat.com / errata/RHSA-2026:33125
access.redhat.com / errata/RHSA-2026:34764
access.redhat.com / errata/RHSA-2026:34788
access.redhat.com / errata/RHSA-2026:34790
access.redhat.com / errata/RHSA-2026:36004
access.redhat.com / errata/RHSA-2026:36005
access.redhat.com / errata/RHSA-2026:36006
access.redhat.com / errata/RHSA-2026:40762
access.redhat.com / errata/RHSA-2026:41921
access.redhat.com / security/cve/CVE-2026-42010
Vendor Advisory
bugzilla.redhat.com / show_bug.cgi
Issue TrackingVendor Advisory
gnutls.org / security-new.html