CVE-2026-27145

6.5 MEDIUM
Published: June 02, 2026 Modified: June 04, 2026
View on NVD

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://go.dev/cl/783621
Source: security@golang.org
https://go.dev/issue/79694
Source: security@golang.org
https://pkg.go.dev/vuln/GO-2026-5037
Source: security@golang.org

4 reference(s) from NVD

Quick Stats

CVSS v3 Score
6.5 / 10.0
EPSS (Exploit Probability)
0.3%
24th percentile
Exploitation Status
Not in CISA KEV