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diff --git a/skip/heimdal/CVE-2018-16860.patch b/skip/heimdal/CVE-2018-16860.patch
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+++ b/skip/heimdal/CVE-2018-16860.patch
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+From c6257cc2c842c0faaeb4ef34e33890ee88c4cbba Mon Sep 17 00:00:00 2001
+From: Isaac Boukris <iboukris@gmail.com>
+Date: Tue, 14 May 2019 09:03:18 -0400
+Subject: [PATCH] CVE-2018-16860 Heimdal KDC: Reject PA-S4U2Self with unkeyed
+ checksum
+
+S4U2Self is an extension to Kerberos used in Active Directory to allow
+a service to request a kerberos ticket to itself from the Kerberos Key
+Distribution Center (KDC) for a non-Kerberos authenticated user
+(principal in Kerboros parlance). This is useful to allow internal
+code paths to be standardized around Kerberos.
+
+S4U2Proxy (constrained-delegation) is an extension of this mechanism
+allowing this impersonation to a second service over the network. It
+allows a privileged server that obtained a S4U2Self ticket to itself
+to then assert the identity of that principal to a second service and
+present itself as that principal to get services from the second
+service.
+
+There is a flaw in Samba's AD DC in the Heimdal KDC. When the Heimdal
+KDC checks the checksum that is placed on the S4U2Self packet by the
+server to protect the requested principal against modification, it
+does not confirm that the checksum algorithm that protects the user
+name (principal) in the request is keyed.  This allows a
+man-in-the-middle attacker who can intercept the request to the KDC to
+modify the packet by replacing the user name (principal) in the
+request with any desired user name (principal) that exists in the KDC
+and replace the checksum protecting that name with a CRC32 checksum
+(which requires no prior knowledge to compute).
+
+This would allow a S4U2Self ticket requested on behalf of user name
+(principal) user@EXAMPLE.COM to any service to be changed to a
+S4U2Self ticket with a user name (principal) of
+Administrator@EXAMPLE.COM. This ticket would then contain the PAC of
+the modified user name (principal).
+
+==================
+CVSSv3 calculation
+==================
+
+CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H (7.5)
+
+=========================
+Workaround and Mitigation
+=========================
+
+If server does not take privileged actions based on Kerberos tickets
+obtained by S4U2Self nor obtains Kerberos tickets via further
+S4U2Proxy requests then this issue cannot be exploited.
+
+Note that the path to an exploit is not generic, the KDC is not harmed
+by the malicious checksum, it is the client service requesting the
+ticket being mislead, because it trusted the KDC to return the correct
+ticket and PAC.
+
+It is out of scope for Samba to describe all of the possible tool
+chains that might be vulnerable. Here are two examples of possible
+exploits in order to explain the issue more clearly.
+
+1). SFU2Self might be used by a web service authenticating an end user
+via OAuth, Shibboleth, or other protocols to obtain a S4U2Self
+Kerberos service ticket for use by any Kerberos service principal the
+web service has a keytab for.  One example is acquiring an AFS token
+by requesting an afs/cell@REALM service ticket for a client via
+SFU2Self.  With this exploit an organization that deploys a KDC built
+from Heimdal (be it Heimdal directly or vendor versions such as found
+in Samba) is vulnerable to privilege escalation attacks.
+
+2). If a server authenticates users using X509 certificates, and then
+uses S4U2Self to obtain a Kerberos service ticket on behalf of the
+user (principal) in order to authorize access to local resources, a
+man-in-the-middle attacker could allow a non-privilaged user to access
+privilaged resources being protected by the server, or privilaged
+resources being protected by a second server, if the first server uses
+the S4U2Proxy extension in order to get a new Kerberos service ticket
+to obtain access to the second server.
+
+In both these scenarios under conditions allowing man-in-the-middle
+active network protocol manipulation, a malicious user could
+authenticate using the non-Kerborized credentials of an unprivileged
+user, and then elevate its privileges by intercepting the packet from
+the server to the KDC and changing the requested user name (principal).
+
+The only Samba clients that use S4U2Self are:
+
+- the "net ads kerberos pac dump" (debugging) tool.
+
+- the CIFS proxy in the deprecated/developer-only NTVFS file
+server. Note this code is not compiled or enabled by default.
+
+In particular, winbindd does *not* use S4U2Self.
+
+Finally, MIT Kerberos and so therefore the experimental MIT KDC backend
+for Samba AD is understood not to be impacted.
+
+===============
+Further Reading
+===============
+
+There is more detail on and a description of the protocols in
+
+[MS-SFU]: Kerberos Protocol Extensions: Service for User and Constrained
+Delegation Protocol
+https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-sfu/
+
+=======
+Credits
+=======
+
+Originally reported by Isaac Boukris and Andrew Bartlett of the Samba
+Team and Catalyst.
+
+Patches provided by Isaac Boukris.
+
+Advisory written by Andrew Bartlett of the Samba Team and Catalyst,
+with contributions from Isaac Boukris, Jeffrey Altman and Jeremy
+Allison.
+
+BUG: https://bugzilla.samba.org/show_bug.cgi?id=13685
+Change-Id: I4ac69ebf0503eb999a7d497a2c30fe4d293a8cc8
+Signed-off-by: Isaac Boukris <iboukris@gmail.com>
+Reviewed-by: Andrew Bartlett <abartlet@samba.org>
+Signed-off-by: Andrew Bartlett <abartlet@samba.org>
+Reviewed-by: Jeffrey Altman <jaltman@auristor.com>
+Signed-off-by: Jeffrey Altman <jaltman@auristor.com>
+---
+ kdc/krb5tgs.c | 7 +++++++
+ 1 file changed, 7 insertions(+)
+
+diff --git a/kdc/krb5tgs.c b/kdc/krb5tgs.c
+index 8318bc0025..14943077a4 100644
+--- a/kdc/krb5tgs.c
++++ b/kdc/krb5tgs.c
+@@ -2031,6 +2031,13 @@ tgs_build_reply(krb5_context context,
+ 		goto out;
+ 	    }
+ 
++	    if (!krb5_checksum_is_keyed(context, self.cksum.cksumtype)) {
++		free_PA_S4U2Self(&self);
++		kdc_log(context, config, 0, "Reject PA-S4U2Self with unkeyed checksum");
++		ret = KRB5KRB_AP_ERR_INAPP_CKSUM;
++		goto out;
++	    }
++
+ 	    ret = _krb5_s4u2self_to_checksumdata(context, &self, &datack);
+ 	    if (ret)
+ 		goto out;