Improper Certificate Validation in Go programming language - CVE-2026-33810

Vulnerability identifier: #VU140605

CSH Severity: Medium

CVSS v4 BT: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2026-33810

CWE-ID: CWE-295

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to bypass certificate name constraints.

The vulnerability exists due to improper certificate validation in the Certificate.Verify function in crypto/x509 when verifying a certificate chain containing excluded DNS constraints and wildcard DNS SANs that use different letter case than the constraint. A remote attacker can present a specially crafted certificate chain to bypass certificate name constraints.

This only affects validation of otherwise trusted certificate chains issued by a root CA in the VerifyOptions.Roots CertPool or in the system certificate pool.

Go programming language
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Desktop 15
Red Hat Enterprise Linux for ARM 64 - Extended Update Support
Red Hat Enterprise Linux for Power, little endian - Extended Update Support
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support
Red Hat Enterprise Linux Server - AUS
Red Hat Enterprise Linux for x86_64 - Extended Update Support
Development Tools Module
Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions
opentelemetry-collector (Red Hat package)
go1.26-openssl-doc
go1.26-openssl
go1.26-openssl-race
go1.26-race
go1.26
go1.26-doc
etcd (Red Hat package)
OpenShift Logging
Red Hat OpenStack

Install security update from vendor's website.

Go programming language - update to 1.26.2
opentelemetry-collector (Red Hat package) - addressed in versions 0.144.0-2.el9_4, 0.144.0-2.el9_6, 0.144.0-2.el10_0
go1.26-openssl-doc - update to 1.26.2-150000.1.6.1
go1.26-openssl - update to 1.26.2-150000.1.6.1
go1.26-openssl-race - update to 1.26.2-150000.1.6.1
go1.26-race - update to 1.26.2-150000.1.9.1
go1.26 - update to 1.26.2-150000.1.9.1
go1.26-doc - update to 1.26.2-150000.1.9.1
etcd (Red Hat package) - update to 3.4.26-9.5.el9ost
OpenShift Logging - update to 6.0.15
Red Hat OpenStack - update to 17.1

• https://pkg.go.dev/vuln/GO-2026-4866
• https://go.dev/cl/763763

• Multiple vulnerabilities in Go programming language
• Red Hat Enterprise Linux 10 update for opentelemetry-collector
• Red Hat Enterprise Linux 9 update for opentelemetry-collector
• Red Hat Enterprise Linux 9 update for opentelemetry-collector
• Multiple vulnerabilities in OpenShift Logging 6.0
• Multiple vulnerabilities in Red Hat OpenStack 17.1 packages
• SUSE update for go1.26
• SUSE update for go1.26-openssl