CVE-2026-3833
Gnutls: gnutls: policy bypass due to case-sensitive nameconstraints comparison
Description
A flaw was found in gnutls. This vulnerability occurs because gnutls performs case-sensitive comparisons of `nameConstraints` labels, specifically for `dNSName` (DNS) or `rfc822Name` (email) constraints within `excludedSubtrees` or `permittedSubtrees`. A remote attacker can exploit this by crafting a leaf certificate with casing differences in the Subject Alternative Name (SAN), leading to a policy bypass where a certificate that should be rejected is instead accepted. This could result in unauthorized access or information disclosure.
INFO
Published Date :
April 30, 2026, 6:16 p.m.
Last Modified :
May 7, 2026, 2:09 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-3833
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | 53f830b8-0a3f-465b-8143-3b8a9948e749 | ||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | MITRE-CVE | ||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update gnutls to the latest version.
- Review and ensure correct nameConstraints usage.
- Apply security patches for certificate validation.
- Validate certificate policies rigorously.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-3833.
| URL | Resource |
|---|---|
| https://access.redhat.com/errata/RHSA-2026:13274 | Issue Tracking Third Party Advisory |
| https://access.redhat.com/security/cve/CVE-2026-3833 | Third Party Advisory |
| https://bugzilla.redhat.com/show_bug.cgi?id=2445763 | Issue Tracking Third Party Advisory |
| https://gitlab.com/gnutls/gnutls/-/issues/1803 | Exploit Issue Tracking Vendor Advisory |
| https://gitlab.com/gnutls/gnutls/-/issues/1803 | Exploit Issue Tracking Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-3833 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-3833
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-3833 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-3833 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
May. 07, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N Added CPE Configuration OR *cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:* *cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:* *cpe:2.3:a:gnu:gnutls:-:*:*:*:*:*:*:* *cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* *cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:* *cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:* *cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:* *cpe:2.3:a:redhat:hardened_images:-:*:*:*:*:*:*:* Added Reference Type Red Hat, Inc.: https://access.redhat.com/errata/RHSA-2026:13274 Types: Issue Tracking, Third Party Advisory Added Reference Type Red Hat, Inc.: https://access.redhat.com/security/cve/CVE-2026-3833 Types: Third Party Advisory Added Reference Type Red Hat, Inc.: https://bugzilla.redhat.com/show_bug.cgi?id=2445763 Types: Issue Tracking, Third Party Advisory Added Reference Type CISA-ADP: https://gitlab.com/gnutls/gnutls/-/issues/1803 Types: Exploit, Issue Tracking, Vendor Advisory Added Reference Type Red Hat, Inc.: https://gitlab.com/gnutls/gnutls/-/issues/1803 Types: Exploit, Issue Tracking, Vendor Advisory -
CVE Modified by [email protected]
May. 03, 2026
Action Type Old Value New Value Added Reference https://access.redhat.com/errata/RHSA-2026:13274 -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Apr. 30, 2026
Action Type Old Value New Value Added Reference https://gitlab.com/gnutls/gnutls/-/issues/1803 -
New CVE Received by [email protected]
Apr. 30, 2026
Action Type Old Value New Value Added Description A flaw was found in gnutls. This vulnerability occurs because gnutls performs case-sensitive comparisons of `nameConstraints` labels, specifically for `dNSName` (DNS) or `rfc822Name` (email) constraints within `excludedSubtrees` or `permittedSubtrees`. A remote attacker can exploit this by crafting a leaf certificate with casing differences in the Subject Alternative Name (SAN), leading to a policy bypass where a certificate that should be rejected is instead accepted. This could result in unauthorized access or information disclosure. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N Added CWE CWE-178 Added Reference https://access.redhat.com/security/cve/CVE-2026-3833 Added Reference https://bugzilla.redhat.com/show_bug.cgi?id=2445763 Added Reference https://gitlab.com/gnutls/gnutls/-/issues/1803