From 0765a9d624119e15c2f527e69098151ba664e5a5 Mon Sep 17 00:00:00 2001 From: Roland Shoemaker Date: Mon, 26 Jan 2026 16:08:00 -0800 Subject: [PATCH] [release-branch.go1.25] crypto/x509: fix single label excluded name constraints handling Only strip labels when both the domain and constraint have more than one label. Fixes #76935 Fixes #77323 Change-Id: Ifdaae2cbe0c57984bb7334a8f08fa33a800e7c27 Reviewed-on: https://go-review.googlesource.com/c/go/+/739400 Auto-Submit: Dmitri Shuralyov Reviewed-by: Damien Neil Reviewed-by: Dmitri Shuralyov LUCI-TryBot-Result: Go LUCI --- src/crypto/x509/name_constraints_test.go | 16 ++++++++++++++++ src/crypto/x509/verify.go | 2 +- 2 files changed, 17 insertions(+), 1 deletion(-) diff --git a/src/crypto/x509/name_constraints_test.go b/src/crypto/x509/name_constraints_test.go index bc91b28401..1f50650267 100644 --- a/src/crypto/x509/name_constraints_test.go +++ b/src/crypto/x509/name_constraints_test.go @@ -1658,6 +1658,22 @@ var nameConstraintsTests = []nameConstraintsTest{ }, expectedError: "\"*.example.com\" is not permitted", }, + // #89: a TLD constraint doesn't exclude unrelated wildcards + { + roots: []constraintsSpec{ + { + bad: []string{"dns:tld"}, + }, + }, + intermediates: [][]constraintsSpec{ + { + {}, + }, + }, + leaf: leafSpec{ + sans: []string{"dns:*.example.com"}, + }, + }, } func makeConstraintsCACert(constraints constraintsSpec, name string, key *ecdsa.PrivateKey, parent *Certificate, parentKey *ecdsa.PrivateKey) (*Certificate, error) { diff --git a/src/crypto/x509/verify.go b/src/crypto/x509/verify.go index 3de9f93b2c..076e82666a 100644 --- a/src/crypto/x509/verify.go +++ b/src/crypto/x509/verify.go @@ -546,7 +546,7 @@ func matchDomainConstraint(domain, constraint string, excluded bool, reversedDom return false, nil } - if excluded && wildcardDomain && len(domainLabels) > 1 && len(constraintLabels) > 0 { + if excluded && wildcardDomain && len(domainLabels) > 1 && len(constraintLabels) > 1 { domainLabels = domainLabels[:len(domainLabels)-1] constraintLabels = constraintLabels[:len(constraintLabels)-1] } -- 2.52.0