diff --git a/openssh-8.7p1-nohostsha1proof.patch b/openssh-8.7p1-nohostsha1proof.patch
new file mode 100644
index 0000000..4f173f1
--- /dev/null
+++ b/openssh-8.7p1-nohostsha1proof.patch
@@ -0,0 +1,100 @@
+diff -up openssh-8.7p1/compat.c.sshrsacheck openssh-8.7p1/compat.c
+--- openssh-8.7p1/compat.c.sshrsacheck 2023-01-12 13:29:06.338710923 +0100
++++ openssh-8.7p1/compat.c 2023-01-12 13:29:06.357711165 +0100
+@@ -43,6 +43,7 @@ void
+ compat_banner(struct ssh *ssh, const char *version)
+ {
+ int i;
++ int forbid_ssh_rsa = 0;
+ static struct {
+ char *pat;
+ int bugs;
+@@ -145,16 +146,21 @@ compat_banner(struct ssh *ssh, const cha
+ };
+
+ /* process table, return first match */
++ forbid_ssh_rsa = (ssh->compat & SSH_RH_RSASIGSHA);
+ ssh->compat = 0;
+ for (i = 0; check[i].pat; i++) {
+ if (match_pattern_list(version, check[i].pat, 0) == 1) {
+ debug_f("match: %s pat %s compat 0x%08x",
+ version, check[i].pat, check[i].bugs);
+ ssh->compat = check[i].bugs;
++ if (forbid_ssh_rsa)
++ ssh->compat |= SSH_RH_RSASIGSHA;
+ return;
+ }
+ }
+ debug_f("no match: %s", version);
++ if (forbid_ssh_rsa)
++ ssh->compat |= SSH_RH_RSASIGSHA;
+ }
+
+ /* Always returns pointer to allocated memory, caller must free. */
+diff -up openssh-8.7p1/compat.h.sshrsacheck openssh-8.7p1/compat.h
+--- openssh-8.7p1/compat.h.sshrsacheck 2021-08-20 06:03:49.000000000 +0200
++++ openssh-8.7p1/compat.h 2023-01-12 13:29:06.358711178 +0100
+@@ -30,7 +30,7 @@
+ #define SSH_BUG_UTF8TTYMODE 0x00000001
+ #define SSH_BUG_SIGTYPE 0x00000002
+ #define SSH_BUG_SIGTYPE74 0x00000004
+-/* #define unused 0x00000008 */
++#define SSH_RH_RSASIGSHA 0x00000008
+ #define SSH_OLD_SESSIONID 0x00000010
+ /* #define unused 0x00000020 */
+ #define SSH_BUG_DEBUG 0x00000040
+diff -up openssh-8.7p1/serverloop.c.sshrsacheck openssh-8.7p1/serverloop.c
+--- openssh-8.7p1/serverloop.c.sshrsacheck 2023-01-12 14:57:08.118400073 +0100
++++ openssh-8.7p1/serverloop.c 2023-01-12 14:59:17.330470518 +0100
+@@ -737,6 +737,10 @@ server_input_hostkeys_prove(struct ssh *
+ else if (ssh->kex->flags & KEX_RSA_SHA2_256_SUPPORTED)
+ sigalg = "rsa-sha2-256";
+ }
++ if (ssh->compat & SSH_RH_RSASIGSHA && sigalg == NULL) {
++ sigalg = "rsa-sha2-512";
++ debug3_f("SHA1 signature is not supported, falling back to %s", sigalg);
++ }
+ debug3_f("sign %s key (index %d) using sigalg %s",
+ sshkey_type(key), ndx, sigalg == NULL ? "default" : sigalg);
+ if ((r = sshbuf_put_cstring(sigbuf,
+diff -up openssh-8.7p1/sshd.c.sshrsacheck openssh-8.7p1/sshd.c
+--- openssh-8.7p1/sshd.c.sshrsacheck 2023-01-12 13:29:06.355711140 +0100
++++ openssh-8.7p1/sshd.c 2023-01-12 13:29:06.358711178 +0100
+@@ -1640,6 +1651,7 @@ main(int ac, char **av)
+ int keytype;
+ Authctxt *authctxt;
+ struct connection_info *connection_info = NULL;
++ int forbid_ssh_rsa = 0;
+
+ #ifdef HAVE_SECUREWARE
+ (void)set_auth_parameters(ac, av);
+@@ -1938,6 +1950,19 @@ main(int ac, char **av)
+ key = NULL;
+ continue;
+ }
++ if (sshkey_type_plain(key->type) == KEY_RSA || sshkey_type_plain(key->type) == KEY_RSA_CERT) {
++ size_t sign_size = 0;
++ u_char *tmp = NULL;
++ u_char data[] = "Test SHA1 vector";
++ int res;
++
++ res = ssh_rsa_sign(key, &tmp, &sign_size, data, sizeof(data), NULL);
++ free(tmp);
++ if (res == SSH_ERR_LIBCRYPTO_ERROR) {
++ logit_f("sshd: ssh-rsa algorithm is disabled");
++ forbid_ssh_rsa = 1;
++ }
++ }
+ if (sshkey_is_sk(key) &&
+ key->sk_flags & SSH_SK_USER_PRESENCE_REQD) {
+ debug("host key %s requires user presence, ignoring",
+@@ -2275,6 +2306,9 @@ main(int ac, char **av)
+
+ check_ip_options(ssh);
+
++ if (forbid_ssh_rsa)
++ ssh->compat |= SSH_RH_RSASIGSHA;
++
+ /* Prepare the channels layer */
+ channel_init_channels(ssh);
+ channel_set_af(ssh, options.address_family);
diff --git a/openssh.spec b/openssh.spec
index fe43beb..93f2613 100644
--- a/openssh.spec
+++ b/openssh.spec
@@ -51,7 +51,7 @@
# Do not forget to bump pam_ssh_agent_auth release if you rewind the main package release to 1
%global openssh_ver 8.7p1
-%global openssh_rel 27
+%global openssh_rel 28
%global pam_ssh_agent_ver 0.10.4
%global pam_ssh_agent_rel 5
@@ -259,6 +259,8 @@ Patch1005: openssh-8.7p1-host-based-auth.patch
# upstream MR:
# https://github.com/openssh/openssh-portable/pull/323
Patch1006: openssh-8.7p1-negotiate-supported-algs.patch
+#
+Patch1007: openssh-8.7p1-nohostsha1proof.patch
License: BSD
Requires: /sbin/nologin
@@ -467,6 +469,8 @@ popd
%patch100 -p1 -b .coverity
+%patch1007 -p1 -b .sshrsacheck
+
autoreconf
pushd pam_ssh_agent_auth-pam_ssh_agent_auth-%{pam_ssh_agent_ver}
autoreconf
@@ -752,6 +756,10 @@ test -f %{sysconfig_anaconda} && \
%endif
%changelog
+* Thu Jan 12 2023 Dmitry Belyavskiy <dbelyavs@redhat.com> - 8.7p1-28
+- Do not try to use SHA1 for host key ownership proof when we don't support it server-side
+ Resolves: rhbz#2088750
+
* Thu Jan 12 2023 Zoltan Fridrich <zfridric@redhat.com> - 8.7p1-27
- Add sk-dummy subpackage for test purposes
Resolves: rhbz#2092780