diff --git a/SOURCES/Fix-KDC-null-deref-on-TGS-inner-body-null-server.patch b/SOURCES/Fix-KDC-null-deref-on-TGS-inner-body-null-server.patch
new file mode 100644
index 0000000..a03f179
--- /dev/null
+++ b/SOURCES/Fix-KDC-null-deref-on-TGS-inner-body-null-server.patch
@@ -0,0 +1,45 @@
+From 0a8dfc380fe3b210662ba1b1d452fcec2f84841b Mon Sep 17 00:00:00 2001
+From: Greg Hudson <ghudson@mit.edu>
+Date: Tue, 3 Aug 2021 01:15:27 -0400
+Subject: [PATCH] Fix KDC null deref on TGS inner body null server
+
+After the KDC decodes a FAST inner body, it does not check for a null
+server.  Prior to commit 39548a5b17bbda9eeb63625a201cfd19b9de1c5b this
+would typically result in an error from krb5_unparse_name(), but with
+the addition of get_local_tgt() it results in a null dereference.  Add
+a null check.
+
+Reported by Joseph Sutton of Catalyst.
+
+CVE-2021-37750:
+
+In MIT krb5 releases 1.14 and later, an authenticated attacker can
+cause a null dereference in the KDC by sending a FAST TGS request with
+no server field.
+
+ticket: 9008 (new)
+tags: pullup
+target_version: 1.19-next
+target_version: 1.18-next
+
+RHEL 7.9 backport of commit: d775c95af7606a51bf79547a94fa52ddd1cb7f49
+---
+ src/kdc/do_tgs_req.c | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/src/kdc/do_tgs_req.c b/src/kdc/do_tgs_req.c
+index 572a2c363..a9a3beb9d 100644
+--- a/src/kdc/do_tgs_req.c
++++ b/src/kdc/do_tgs_req.c
+@@ -204,6 +204,11 @@ process_tgs_req(krb5_kdc_req *request, krb5_data *pkt,
+         status = "FIND_FAST";
+         goto cleanup;
+     }
++    if (sprinc == NULL) {
++        status = "NULL_SERVER";
++        errcode = KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN;
++        goto cleanup;
++    }
+ 
+     errcode = get_local_tgt(kdc_context, &sprinc->realm, header_server,
+                             &local_tgt, &local_tgt_storage);
diff --git a/SPECS/krb5.spec b/SPECS/krb5.spec
index e72c876..83ca697 100644
--- a/SPECS/krb5.spec
+++ b/SPECS/krb5.spec
@@ -12,7 +12,7 @@
 Summary: The Kerberos network authentication system
 Name: krb5
 Version: 1.15.1
-Release: 50%{?dist}
+Release: 51%{?dist}
 
 # - Maybe we should explode from the now-available-to-everybody tarball instead?
 # http://web.mit.edu/kerberos/dist/krb5/1.13/krb5-1.13.2-signed.tar
@@ -140,6 +140,7 @@ Patch227: Add-PKINIT-test-case-for-generic-client-cert.patch
 Patch228: Do-expiration-warnings-for-all-init_creds-APIs.patch
 Patch229: Remove-vestigial-svr_principal.c-code.patch
 Patch230: Fix-LDAP-policy-enforcement-of-pw_expiration.patch
+Patch231: Fix-KDC-null-deref-on-TGS-inner-body-null-server.patch
 
 License: MIT
 URL: http://web.mit.edu/kerberos/www/
@@ -413,6 +414,7 @@ ONLY by kerberos itself. Do not depend on this package.
 %patch228 -p1 -b .Do-expiration-warnings-for-all-init_creds-APIs
 %patch229 -p1 -b .Remove-vestigial-svr_principal.c-code
 %patch230 -p1 -b .Fix-LDAP-policy-enforcement-of-pw_expiration
+%patch231 -p1 -b .Fix-KDC-null-deref-on-TGS-inner-body-null-server
 
 ln NOTICE LICENSE
 
@@ -920,6 +922,10 @@ exit 0
 %{_libdir}/libkadm5srv_mit.so.*
 
 %changelog
+* Wed Oct 20 2021 Antonio Torres <antorres@redhat.com> - 1.15.1-51
+- Fix KDC null deref on TGS inner body null server (CVE-2021-37750)
+- Resolves: #1997599
+
 * Mon Apr 06 2020 Robbie Harwood <rharwood@redhat.com> - 1.15.1-50
 - Disable smoke tests on s390x and remove sleep
 - Resolves: #1782492