Improper Authorization in Go programming language - CVE-2026-27137
Published: March 19, 2026
Vulnerability identifier: #VU124115
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-27137
CWE-ID: CWE-285
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Google
Affected software:
Go programming language
Go programming language
Detailed vulnerability description
The vulnerability allows a remote attacker to bypass email address constraints during X.509 certificate chain verification.
The vulnerability exists due to improper enforcement of email constraints in crypto/x509 when verifying certificate chains containing multiple email address constraints with shared local parts but different domains. A remote attacker can present a certificate chain with malformed email constraints to cause only the last constraint to be applied, leading to improper validation.
This issue only affects Go 1.26 and requires the certificate chain to chain to a trusted root. A trusted CA must issue the malicious certificate.
How to mitigate CVE-2026-27137
Install security update from vendor's website.