CVE-2026-27145
MEDIUMDescription
(*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 to fix
This vulnerability affects an unusually large number of packages. The highest-confidence fixes are shown above; the full list is longer. Check the referenced advisories for complete coverage.
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Exploit Intelligence
Moderate risk: more likely to be exploited than 46% of all known CVEs.
References
- go.dev
- go.dev
- groups.google.com
- pkg.go.dev
- access.redhat.com
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Related Vulnerabilities
Other CWE-606 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2023-3446 | Medium | 5.3 | 6.5% | - | Fix |
| CVE-2023-5678 | Medium | 5.3 | 4.5% | - | Fix |
| CVE-2023-3817 | Medium | 5.3 | 3.0% | - | Fix |
| CVE-2024-43499 | High | 7.5 | 2.6% | - | Fix |
| CVE-2023-6237 | Medium | 5.9 | 2.3% | - | Fix |
| CVE-2026-1519 | High | 7.5 | 1.6% | - | Fix |
Common questions
How do I fix CVE-2026-27145?
Published advisories record a fix for 548 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2026-27145 being actively exploited?
Not that we know of. CVE-2026-27145 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.59% is the estimated probability that it will be exploited in the next 30 days. That is higher than 46% of all scored CVEs.
How severe is CVE-2026-27145?
CVE-2026-27145 has a CVSS v3 base score of 6.5, rated moderate. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-27145 affect?
Published advisories record a fix for aap-metrics-utility (Rocky), aap-metrics-utility (Red Hat / RHEL), ansible-automation-platform-installer (Rocky), ansible-automation-platform-installer (Red Hat / RHEL), and 544 more. The list on this page is capped, so there may be more.
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-27.