CVE-2026-27145
highpriority · track · 10EPSS 0.006 · 48 %ileexploit · PoCDEEUFRRUUSEPSS · scored 2026-10-27
(*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
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.5–7.5
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
exploits (1)
Public proof-of-concept and weaponised exploit code.
- HORKimhab/CVE-2026-27145CVE-2026-27145 - DraftPoC · poc_in_github
affected products (26)
Products and version ranges known to be affected.
- Red Hat Enterprise Linux Advanced Cluster Management for Kubernetesall versionscert_bundDEcpe:/o:redhat:enterprise_linux:advanced_cluster_management_for_kubernetes
- Red Hat Enterprise Linux Multicluster Engine for Kubernetesall versionscert_bundDEcpe:/o:redhat:enterprise_linux:multicluster_engine_for_kubernetes
- Red Hat OpenShift Container Platformall versionscert_bundDEcpe:/a:redhat:openshift:container_platform
advisories (4)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-1776Golang Go: Mehrere SchwachstellenDeutsch2026-06-02csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Golang Go ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen, um einen Denial of Service durchzuführen, und um falsche Informationen darzustellen.
- BIT-golang-2026-27145Inefficient candidate hostname parsing in crypto/x5092026-06-05vendor · osvUS
(*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.
- CERTFR-2026-AVI-1385Multiples vulnérabilités dans les produits VMwareFrançais2026-10-26vendor · certfrFR
- GO-2026-5037Inefficient candidate hostname parsing in crypto/x5092026-06-02vendor · osvUS
(*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.
also known as (6)
Other names and identifiers for this entity.
- CNNVD-202606-382cnnvd
- EUVD-2026-34038enisa_euvd
- BDU:2026-09275fstec_bdu
- GHSA-4279-q6mj-392renisa_euvd
- BIT-golang-2026-27145osv
- GO-2026-5037osv
sources
Which sources assert this record, and when.
references (107)
External citations — patches, advisories, analysis.
- https://go.dev/Patchcnnvd
- https://go.dev/cl/783621cnnvd
- https://go.dev/issue/79694cnnvd
- https://groups.google.com/g/golang-announce/c/tKs3rmcBcKwcnnvd
- https://pkg.go.dev/vuln/GO-2026-5037cnnvd
- https://go.dev/cl/783621enisa_euvd
- https://go.dev/issue/79694enisa_euvd
- https://groups.google.com/g/golang-announce/c/tKs3rmcBcKwenisa_euvd
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