CVE-2026-27145 — MEDIUM (6.5)

Vulnerability Description

(*x509.Certificate).VerifyHostname previously called matchHostnames in a loop over all DNS Subject Alternative Name (SAN) entries. This caused strings.Split(host, ".") to execute repeatedly on the same input hostname. With a large DNS SAN list, verification costs scaled quadratically based on the number of SAN entries multiplied by the hostname's label count. Because x509.Verify validates hostnames before building the certificate chain, this overhead occurred even for untrusted certificates.

CVSS Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

NONE

Integrity

LOW

Availability

HIGH

Related Weaknesses (CWE)

CWE-606

References

FAQ

What is CVE-2026-27145?

CVE-2026-27145 is a vulnerability with a CVSS score of 6.5 (MEDIUM). (*x509.Certificate).VerifyHostname previously called matchHostnames in a loop over all DNS Subject Alternative Name (SAN) entries. This caused strings.Split(host, ".") to execute repeatedly on the sam...

How severe is CVE-2026-27145?

CVE-2026-27145 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-27145?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.