{"schema_version":"1.9.0","id":"BIT-golang-2026-27145","published":"2026-06-05T05:44:57.398Z","modified":"2026-09-04T09:30:04.143866602Z","aliases":["CVE-2026-27145","GO-2026-5037"],"summary":"Inefficient candidate hostname parsing in crypto/x509","details":"(*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.","affected":[{"package":{"name":"golang","ecosystem":"Bitnami","purl":"pkg:bitnami/golang"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.25.11"},{"introduced":"1.26.0-0"},{"fixed":"1.26.4"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/golang/BIT-golang-2026-27145.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H"}]}],"references":[{"type":"WEB","url":"https://go.dev/cl/783621"},{"type":"WEB","url":"https://go.dev/issue/79694"},{"type":"WEB","url":"https://groups.google.com/g/golang-announce/c/tKs3rmcBcKw"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27145"},{"type":"WEB","url":"https://pkg.go.dev/vuln/GO-2026-5037"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:33574"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:34357"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:34359"},{"type":"WEB","url":"https://access.redhat.com/security/cve/CVE-2026-27145"},{"type":"WEB","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2484207"},{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27145.json"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:35832"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:36317"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:36648"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:29981"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:36797"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:38995"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:39005"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:39573"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:23262"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:23264"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:39879"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:41030"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:41036"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:41930"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:42043"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:42047"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:42049"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:42050"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:42051"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:42079"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:42080"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:42082"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:42142"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:42150"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:42151"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:42240"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:42644"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:42946"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:44622"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:46394"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:46395"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:47149"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:47735"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:47737"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:29980"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:49703"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:49705"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:49729"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:49744"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:49765"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:49770"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:50205"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:50319"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:51057"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:51187"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:52946"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:53374"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:53412"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:53413"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:53415"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:53416"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:53530"},{"type":"WEB","url":"https://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