https://sources.debian.org/data/main/liba/libapache-mod-auth-kerb/5.4-2.5/debian/patches/0011-Always-use-NONE-replay-cache-type.patch
https://bugs.gentoo.org/830208

From: Sam Hartman <hartmans@debian.org>
Date: Mon, 23 Nov 2020 09:30:22 -0500
Subject: Always use NONE replay cache type

It's 2020.  Any MIT Kerberos in the wild supports the none replay
cache type.  The previous code used an internal function to detect
that replay cache type; that function is no longer available.
Instead, assume it is present.

An alternative would be to enable the default replay cache.  It was
originally disabled because of problems between Microsoft
authenticators and 2004-era MIT Kerberos 1.3.  That's probably a good
idea.  It probably closes off security attacks, although analyzing the
impact of replays in cases where neither channel binding nor
per-message services are used is difficult.  I believe that a replay
cache is not strictly necessary in the common configuration where
mod-auth-kerb is used over a TLS-protected connection where the client
properly verifies the TLS certificate presented by the server prior to
sending a GSS token.

I have elected not to enable replay cache to affect a minimal change.
--- a/src/mod_auth_kerb.c
+++ b/src/mod_auth_kerb.c
@@ -2061,28 +2061,6 @@
    return ret;
 }
 
-static int
-have_rcache_type(const char *type)
-{
-   krb5_error_code ret;
-   krb5_context context;
-   krb5_rcache id = NULL;
-   int found;
-
-   ret = krb5_init_context(&context);
-   if (ret)
-      return 0;
-
-   ret = krb5_rc_resolve_full(context, &id, "none:");
-   found = (ret == 0);
-
-   if (ret == 0)
-      krb5_rc_destroy(context, id);
-   krb5_free_context(context);
-
-   return found;
-}
-
 /*************************************************************************** 
  Module Setup/Configuration
  ***************************************************************************/
@@ -2143,7 +2121,7 @@
 #ifndef HEIMDAL
    /* Suppress the MIT replay cache.  Requires MIT Kerberos 1.4.0 or later.
       1.3.x are covered by the hack overiding the replay calls */
-   if (getenv("KRB5RCACHETYPE") == NULL && have_rcache_type("none"))
+   if (getenv("KRB5RCACHETYPE") == NULL)
       putenv(strdup("KRB5RCACHETYPE=none"));
 #endif
 }
@@ -2185,7 +2163,7 @@
 #ifndef HEIMDAL
    /* Suppress the MIT replay cache.  Requires MIT Kerberos 1.4.0 or later.
       1.3.x are covered by the hack overiding the replay calls */
-   if (getenv("KRB5RCACHETYPE") == NULL && have_rcache_type("none"))
+   if (getenv("KRB5RCACHETYPE") == NULL)
       putenv(strdup("KRB5RCACHETYPE=none"));
 #endif
 #ifdef STANDARD20_MODULE_STUFF