From: Jan Klemkow Subject: Re: [diff] httpd: pass through dn from tls client cert to fcgi To: Jack Burton Cc: tech@openbsd.org Date: Thu, 30 Apr 2026 20:07:58 +0200 On Thu, Apr 30, 2026 at 03:26:20PM +0930, Jack Burton wrote: > On Wed, 29 Apr 2026 21:49:29 +0200 > Jan Klemkow wrote: > > I also like this feature and also thought about it in the past. > > > > But, I guess a certificate where the subject is NULL, may crash the > > httpd? > > Interesting. Well caught. I hadn't thought of that, as it makes no > sense at all to have a *client* certificate without a subject field. > Nevertheless, RFC 5280 does not prohibit it, so I guess it's possible > and therefore it makes sense to check for it. In this scenario it does not matter, if its legal or not to have a subject-less client certificate. The important question is: Can an attacker craft a certificate which leads to NULL in ->subject, which he can use to DoS the httpd?