Go 1.26.x crypto/x509 DNS Constraint Case Sensitivity
CVE-2026-33810 Published on April 8, 2026
Case-sensitive excludedSubtrees name constraints cause Auth Bypass in crypto/x509
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 CA in the VerifyOptions.Roots CertPool, or in the system certificate pool.
Vulnerability Analysis
CVE-2026-33810 is exploitable with network access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity and availability.
Weakness Type
Improper Validation of Unsafe Equivalence in Input
The product receives an input value that is used as a resource identifier or other type of reference, but it does not validate or incorrectly validates that the input is equivalent to a potentially-unsafe value.
Products Associated with CVE-2026-33810
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Affected Versions
Go standard library crypto/x509:- Version 1.26.0-0 and below 1.26.2 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.