CVE-2026-27145
Published: June 5, 2026Last modified: July 8, 2026
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.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 6.5 |
| Attack Vector | NETWORK |
| Attack complexity | HIGH |
| Privileges required | NONE |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | NONE |
| Integrity impact | LOW |
| Availability impact | HIGH |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | go | Fixed (1.25.11-r0) |
| 25 LTS | go | Fixed (1.25.11-r0) | |
| Stream | go | Fixed (1.26.4-r0) | |
| Hardened Containers | 23 LTS | go | Fixed (1.25.11-r0) |
| 25 LTS | go | Fixed (1.25.11-r0) | |
| Stream | go | Fixed (1.26.4-r0) |
References
- https://access.redhat.com/errata/RHSA-2026:23262
- https://access.redhat.com/errata/RHSA-2026:23264
- https://access.redhat.com/errata/RHSA-2026:29981
- https://access.redhat.com/errata/RHSA-2026:33574
- https://access.redhat.com/errata/RHSA-2026:34357
- https://access.redhat.com/errata/RHSA-2026:34359
- https://access.redhat.com/errata/RHSA-2026:35832
- https://access.redhat.com/errata/RHSA-2026:36317
- https://access.redhat.com/errata/RHSA-2026:36648
- https://access.redhat.com/errata/RHSA-2026:36797
- https://access.redhat.com/errata/RHSA-2026:38995
- https://access.redhat.com/errata/RHSA-2026:39005
- https://access.redhat.com/errata/RHSA-2026:39573
- https://access.redhat.com/errata/RHSA-2026:39879
- https://access.redhat.com/errata/RHSA-2026:41030
- https://access.redhat.com/errata/RHSA-2026:41036
- https://access.redhat.com/errata/RHSA-2026:41930
- https://access.redhat.com/errata/RHSA-2026:42043
- https://access.redhat.com/errata/RHSA-2026:42047
- https://access.redhat.com/errata/RHSA-2026:42049
- https://access.redhat.com/errata/RHSA-2026:42050
- https://access.redhat.com/errata/RHSA-2026:42051
- https://access.redhat.com/errata/RHSA-2026:42079
- https://access.redhat.com/errata/RHSA-2026:42080
- https://access.redhat.com/errata/RHSA-2026:42082
- https://access.redhat.com/errata/RHSA-2026:42142
- https://access.redhat.com/errata/RHSA-2026:42150
- https://access.redhat.com/errata/RHSA-2026:42151
- https://access.redhat.com/errata/RHSA-2026:42240
- https://access.redhat.com/errata/RHSA-2026:42644
- https://access.redhat.com/errata/RHSA-2026:42946
- https://access.redhat.com/security/cve/CVE-2026-27145
- https://bugzilla.redhat.com/show_bug.cgi?id=2484207
- https://go.dev/cl/783621
- https://go.dev/issue/79694
- https://groups.google.com/g/golang-announce/c/tKs3rmcBcKw
- https://pkg.go.dev/vuln/GO-2026-5037
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27145.json