On Mon, Apr 20, 2026 at 06:20:52PM +0200, Steffen Nurpmeso wrote:
Kevin J. McCarthy wrote in
<[email protected]>:
|RFC 6125 section 6.4.4 says the client should not check the
|Common Name if the cert contains any DNS entries.

Note RFC 9525 completely forbids commonName, and .. now my memory
is a bit flaky, but i am pretty sure i saw messages on some IETF
list fly by, where people who have an idea claimed they have not
seen this in quite some time.
I (i created the commit on 2023-11-09, [2187cf6eff6], so likely
around then i must have read all that) wrote:

+   /* RFC 2818, 3.1.  Server Identity
+    *    If a subjectAltName extension of type dNSName is present, that MUST
+    *    be used as the identity. Otherwise, the (most specific) Common Name
+    *    field in the Subject field of the certificate MUST be used. Although
+    *    the use of the Common Name is existing practice, it is deprecated and
+    *    Certification Authorities are encouraged to use the dNSName instead.
+    *
+    * RFC 9525:
+    *    The server identity can only be expressed in the subjectAltNames
+    *    extension; it is no longer valid to use the commonName RDN, known
+    *    as CN-ID in [VERIFY=RFC 6125=predecessor]. */

thank you steffen.

I think for now, I will commit the change to master.  It's probably safe
by now to make the change, but I don't think the severity of the issue
merits making the change in a stable release.

--
Kevin J. McCarthy
GPG Fingerprint: 8975 A9B3 3AA3 7910 385C  5308 ADEF 7684 8031 6BDA

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