How severe is CVE-2026-27145?

CVE-2026-27145 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.

Is CVE-2026-27145 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-27145?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-27145 have an EU (EUVD) identifier?

Yes. CVE-2026-27145 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-34038.

When was CVE-2026-27145 published?

CVE-2026-27145 was published on 2026-06-02 and last updated on 2026-07-08.

CVE-2026-27145

CVE-2026-27145 is a medium-severity vulnerability with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-606.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 1% (55th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-34038
Weakness: CWE-606
Published: 2026-06-02
Last modified: 2026-07-08

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.

Frequently asked questions

What is CVE-2026-27145?: (*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.
How severe is CVE-2026-27145?: CVE-2026-27145 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.
Is CVE-2026-27145 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-27145?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-27145 have an EU (EUVD) identifier?: Yes. CVE-2026-27145 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-34038.
When was CVE-2026-27145 published?: CVE-2026-27145 was published on 2026-06-02 and last updated on 2026-07-08.

References

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