# CVE-2026-42011: GnuTLS name constraint bypass in certificate validation

Source: https://junglewise.ai/threats/cve-2026-42011-gnutls-name-constraint-bypass-in-certificate-validation  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-07. Updated: 2026-05-27  
License: CC BY 4.0 with a link back

CVE-2026-42011 · Severity: high · CVSS 7.4 · Published 2026-05-07

A security flaw was identified in GnuTLS, a widely used software library that handles secure internet connections (SSL/TLS). The vulnerability allows an attacker to bypass security checks that verify if a digital certificate is authorized to represent a specific domain. This could allow a malicious actor to impersonate legitimate websites or intercept encrypted communications, potentially leading to the theft of sensitive data.

Technologies: [Red Hat Enterprise Linux 10](https://junglewise.ai/threats/technologies/enterprise-linux-10), [Red Hat Enterprise Linux 8](https://junglewise.ai/threats/technologies/enterprise-linux-8), [Red Hat Enterprise Linux 9](https://junglewise.ai/threats/technologies/enterprise-linux-9). Vendors: [Red Hat](https://junglewise.ai/threats/vendors/red-hat).

## Quick answers

**Is CVE-2026-42011 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-42011 being exploited in the wild.

**How severe is CVE-2026-42011?** High severity, with a CVSS score of 7.4, published 7 May 2026.

**Which products and versions are affected?** Red Hat Enterprise Linux 8 8.10.

**Is there a fix for CVE-2026-42011?** A patch was published on 2026-05-02: Initial Red Hat Hardened Images update released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-42011 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-42011?** Check whether you run Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8 or Red Hat Enterprise Linux 9 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A vulnerability exists in GnuTLS due to improper certificate validation (CWE-295) specifically related to X.509 name constraint handling. The flaw occurs when permitted name constraints are incorrectly ignored if previous Certificate Authorities (CAs) in the chain only specified excluded name constraints. A remote attacker can exploit this logic error to present a certificate that should be rejected, effectively bypassing critical name constraint checks. This can lead to the acceptance of invalid certificates, enabling spoofing or man-in-the-middle (MitM) attacks. The issue has been addressed in Red Hat Enterprise Linux versions 8, 9, and 10 via security updates such as RHSA-2026:20611.

## Affected products

- GnuTLS gnutls 3.6.x, 3.8.x
- Red Hat Enterprise Linux 8 8.10
- Red Hat Enterprise Linux 9
- Red Hat Enterprise Linux 10

## Timeline

- 2026-05-02: patched: Initial Red Hat Hardened Images update released
- 2026-05-06: disclosed: Bug reported to Red Hat Bugzilla
- 2026-05-07: advisory: NVD published the CVE record
- 2026-05-26: patched: General availability of patches for RHEL 8, 9, and 10

## References

- [https://access.redhat.com/errata/RHSA-2026:13274](https://access.redhat.com/errata/RHSA-2026:13274)
- [https://access.redhat.com/errata/RHSA-2026:20611](https://access.redhat.com/errata/RHSA-2026:20611)
- [https://access.redhat.com/security/cve/CVE-2026-42011](https://access.redhat.com/security/cve/CVE-2026-42011)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2467437](https://bugzilla.redhat.com/show_bug.cgi?id=2467437)

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