High severity · published Apr 8, 2026
CVE-2026-33810
Case-sensitive excludedSubtrees name constraints cause Auth Bypass in crypto/x509
8.2
CVSS
0.3%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 27% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CR
crypto/x509 · Go standard library
1.26.0-0 before 1.26.2 · source: vendor
GO
GO · Golang
1.26.0 before 1.26.2 · source: NVD
AI
Assisted Installer for Red Hat OpenShift Container Platform 2 · Red Hat
All versions, or not specified · source: CISA
BF
Builds for Red Hat OpenShift 1.6.0 · Red Hat
All versions, or not specified · source: CISA
CO
Compliance Operator 1 · Red Hat
All versions, or not specified · source: CISA
CC
Confidential Compute Attestation · Red Hat
All versions, or not specified · source: CISA
C4
Cryostat 4 on RHEL 9 · Red Hat
All versions, or not specified · source: CISA
DV
Deployment Validation Operator · Red Hat
All versions, or not specified · source: CISA
FA
Fence Agents Remediation Operator · Red Hat
All versions, or not specified · source: CISA
FI
File Integrity Operator · Red Hat
All versions, or not specified · source: CISA
G3
Gatekeeper 3 · Red Hat
All versions, or not specified · source: CISA
HH
HawtIO HawtIO 4.4.0 · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33810
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-33810
Patch
https://go.dev/cl/763763
Issue Tracking
https://go.dev/issue/78332
Mailing List
https://groups.google.com/g/golang-announce/c/0uYbvbPZRWU
Vendor Advisory
https://pkg.go.dev/vuln/GO-2026-4866
www.openwall.com
http://www.openwall.com/lists/oss-security/2026/04/19/4
www.openwall.com
http://www.openwall.com/lists/oss-security/2026/04/20/1
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