Medium severity · published Mar 6, 2026
CVE-2026-27138
Panic in name constraint checking for malformed certificates in crypto/x509
5.9
CVSS
0.4%
EPSS
No
On KEV
Description
Certificate verification can panic when a certificate in the chain has an empty DNS name and another certificate in the chain has excluded name constraints. This can crash programs that are either directly verifying X.509 certificate chains, or those that use TLS.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 30% 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 1.26.1 · source: vendor
GO
GO · Golang
1.26.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27138
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-27138
Mailing List
https://go.dev/cl/752183
Issue Tracking
https://go.dev/issue/77953
Release Notes
https://groups.google.com/g/golang-announce/c/EdhZqrQ98hk
Vendor Advisory
https://pkg.go.dev/vuln/GO-2026-4600
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