CVE-2026-27145
Inefficient candidate hostname parsing in crypto/x509
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.
INFO
Published Date :
June 2, 2026, 11:16 p.m.
Last Modified :
June 2, 2026, 11:16 p.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-27145
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Refactor hostname verification logic to optimize performance.
- Reduce repeated string splitting on input hostnames.
- Ensure efficient processing of DNS Subject Alternative Names.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-27145.
| URL | Resource |
|---|---|
| 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 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-27145 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-27145
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-27145 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-27145 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Jun. 02, 2026
Action Type Old Value New Value Added 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. Added Reference https://go.dev/cl/783621 Added Reference https://go.dev/issue/79694 Added Reference https://groups.google.com/g/golang-announce/c/tKs3rmcBcKw Added Reference https://pkg.go.dev/vuln/GO-2026-5037