CVE-2026-27145
Inefficient candidate hostname parsing in crypto/x509
Vexday Risk Score
33Attention
SSVC decision (CISA)
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PoC available → attend closely
CVSS 6.5EPSS 0.6%KEV nãoPoC públicaNuclei —Metasploit —Patch —
Lifecycle
02 Jun 2026Published on NVD
03 Jun 2026Public PoC
Recommendation: Plan a near-term fix — a public PoC already exists.
(*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:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Affected products
Go standard library · crypto/x509public PoCs found — 1
githubgithub.com/HORKimhab/CVE-2026-27145★ 0⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
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