Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:NSummary
CVE-2026-33810 is a high-severity Improper Certificate Validation (CWE-295) vulnerability in Golang Go. Its CVSS base score is 8.2 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Adversary-in-the-Middle (T1557); ranked at the 27th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SC-17 (Public Key Infrastructure Certificates) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-33810 is a vulnerability in the Go programming language's certificate verification process, specifically within the crypto/x509 package. When verifying a certificate chain that includes excluded DNS constraints, these constraints are not correctly applied to wildcard DNS Subject Alternative Names (SANs) that use a different case than the constraint. This issue only impacts validation of certificate chains that would otherwise be trusted, issued by root CAs present in the VerifyOptions.Roots CertPool or the system certificate pool. The vulnerability carries a CVSS v3.1 base score of 8.2 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N) and is associated with CWE-295 (Improper Certificate Validation). It was published on 2026-04-08.
Remote attackers require no privileges or user interaction to exploit this vulnerability over a network connection with low complexity. By presenting a malicious certificate chain from a trusted root CA, an attacker can bypass DNS constraints on wildcard SANs due to case insensitivity mishandling, leading to successful validation of an otherwise invalid certificate. This enables high-impact confidentiality violations, such as unauthorized access to encrypted communications, and low-impact integrity violations, potentially allowing limited tampering or impersonation in TLS contexts.
Advisories and patches for mitigation are detailed in official Go resources, including the fix commit at https://go.dev/cl/763763, the tracking issue at https://go.dev/issue/78332, the Golang announce mailing list at https://groups.google.com/g/golang-announce/c/0uYbvbPZRWU, the Go vulnerability database entry GO-2026-4866 at https://pkg.go.dev/vuln/GO-2026-4866, and an OSS-security mailing list post at http://www.openwall.com/lists/oss-security/2026/04/19/4. Security practitioners should update to a patched version of Go that incorporates the fix to ensure proper constraint enforcement during certificate chain validation.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-20024
Vulnerability Data
When verifying a certificate chain containing excluded DNS constraints, these constraints are not correctly applied to wildcard DNS SANs which use a different case than the constraint. This only affects validation of otherwise trusted certificate chains, issued by a root…
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CA in the VerifyOptions.Roots CertPool, or in the system certificate pool.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 12 hardening rules · 3 OS baselines
V5.2.2V9.1.3V10.4.6V2.2.2
Mitigating Controls (NIST 800-53 r5) AI
PKI certificate issuance and acquisition under an approved policy establishes the trusted roots and processes needed for correct validation.
SI-10 requires validity checks on information inputs, directly stopping unsafe equivalence validation failures for identifiers and references.
Protecting session authenticity depends on cryptographic mechanisms whose trust depends on correct certificate validation.
Requiring confidentiality and integrity protection of transmitted data drives use of properly validated certificates in protocols such as TLS.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Certificate-based authentication of users/services/hardware directly depends on correct validation.
Proper certificate validation is a core mechanism for protecting data-in-transit confidentiality and integrity.
Secure development practices explicitly include implementing correct certificate validation logic.
Assessing authenticity/integrity of acquired software often relies on code-signing certificate validation.
Identity assertions conveyed via certificates require validation to be verified.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect unsafe equivalence flaws but does not prevent them at design time.
Requiring issuance and validation of public-key certificates under an approved policy reduces the chance that certificates with improper validation will be trusted.
Application security requirements can mandate input validation rules that prevent unsafe equivalence checks.
Secure architecture principles include proper input validation and canonicalization to avoid unsafe equivalence.
Secure coding standards directly require correct validation of resource identifiers and equivalence checks.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Oracle Linux 8 (3 rules)
- V-248574 YUM must be configured to prevent the installation of patches, service packs, device drivers, or OL 8 system components that have not been digitally signed using a certificate that is recognized and approved by the organization. prevents CWE-295
- V-248531 OL 8, for PKI-based authentication, must validate certificates by constructing a certification path (which includes status information) to an accepted trust anchor. prevents CWE-295
- V-248575 OL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-295
RHEL 7 (2 rules)
- V-204447 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-295
- V-204448 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-295
RHEL 8 (2 rules)
- V-230264 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-295
- V-230265 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-295