From: "Theo Gaige (Schneider Electric)" <[email protected]>

Backport patch from [1] matching CVE description in [2] and change described
in release note [3].

[1] 
https://github.com/openssh/openssh-portable/commit/fd1c7e131f331942d20f42f31e79912d570081fa

[2] https://security-tracker.debian.org/tracker/CVE-2026-35387

[3] https://www.openssh.org/releasenotes.html#10.3p1

Signed-off-by: Theo Gaige (Schneider Electric) <[email protected]>
Reviewed-by: Bruno Vernay <[email protected]>
---
 .../openssh/openssh/CVE-2026-35387.patch      | 205 ++++++++++++++++++
 .../openssh/openssh_9.6p1.bb                  |   1 +
 2 files changed, 206 insertions(+)
 create mode 100644 
meta/recipes-connectivity/openssh/openssh/CVE-2026-35387.patch

diff --git a/meta/recipes-connectivity/openssh/openssh/CVE-2026-35387.patch 
b/meta/recipes-connectivity/openssh/openssh/CVE-2026-35387.patch
new file mode 100644
index 0000000000..c4806bd993
--- /dev/null
+++ b/meta/recipes-connectivity/openssh/openssh/CVE-2026-35387.patch
@@ -0,0 +1,205 @@
+From faaf123656513f16994853379c388ad8cc850f8c Mon Sep 17 00:00:00 2001
+From: "[email protected]" <[email protected]>
+Date: Thu, 2 Apr 2026 07:48:13 +0000
+Subject: [PATCH] upstream: correctly match ECDSA signature algorithms against
+
+algorithm allowlists: HostKeyAlgorithms, PubkeyAcceptedAlgorithms and
+HostbasedAcceptedAlgorithms.
+
+Previously, if any ECDSA type (say "ecdsa-sha2-nistp521") was
+present in one of these lists, then all ECDSA algorithms would
+be permitted.
+
+Reported by Christos Papakonstantinou of Cantina and Spearbit.
+
+OpenBSD-Commit-ID: c790e2687c35989ae34a00e709be935c55b16a86
+
+CVE: CVE-2026-35387
+Upstream-Status: Backport 
[https://github.com/openssh/openssh-portable/commit/fd1c7e131f331942d20f42f31e79912d570081fa]
+Signed-off-by: Theo Gaige (Schneider Electric) <[email protected]>
+---
+ auth2-hostbased.c  |  9 +++++----
+ auth2-pubkey.c     |  9 +++++----
+ auth2-pubkeyfile.c | 26 +++++++++++++++-----------
+ sshconnect2.c      | 28 ++++++++++++++++++----------
+ 4 files changed, 43 insertions(+), 29 deletions(-)
+
+diff --git a/auth2-hostbased.c b/auth2-hostbased.c
+index 06bb464ff..02eeed3f0 100644
+--- a/auth2-hostbased.c
++++ b/auth2-hostbased.c
+@@ -1,4 +1,4 @@
+-/* $OpenBSD: auth2-hostbased.c,v 1.52 2023/03/05 05:34:09 dtucker Exp $ */
++/* $OpenBSD: auth2-hostbased.c,v 1.57 2026/04/02 07:48:13 djm Exp $ */
+ /*
+  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
+  *
+@@ -95,9 +95,10 @@ userauth_hostbased(struct ssh *ssh, const char *method)
+               error_f("cannot decode key: %s", pkalg);
+               goto done;
+       }
+-      if (key->type != pktype) {
+-              error_f("type mismatch for decoded key "
+-                  "(received %d, expected %d)", key->type, pktype);
++      if (key->type != pktype || (sshkey_type_plain(pktype) == KEY_ECDSA &&
++          sshkey_ecdsa_nid_from_name(pkalg) != key->ecdsa_nid)) {
++              error_f("key type mismatch for decoded key "
++                  "(received %s, expected %s)", sshkey_ssh_name(key), pkalg);
+               goto done;
+       }
+       if (match_pattern_list(pkalg, options.hostbased_accepted_algos, 0) != 
1) {
+diff --git a/auth2-pubkey.c b/auth2-pubkey.c
+index 3f49e1df3..1e07ff74e 100644
+--- a/auth2-pubkey.c
++++ b/auth2-pubkey.c
+@@ -1,4 +1,4 @@
+-/* $OpenBSD: auth2-pubkey.c,v 1.119 2023/07/27 22:25:17 djm Exp $ */
++/* $OpenBSD: auth2-pubkey.c,v 1.126 2026/04/02 07:48:13 djm Exp $ */
+ /*
+  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
+  * Copyright (c) 2010 Damien Miller.  All rights reserved.
+@@ -148,9 +148,10 @@ userauth_pubkey(struct ssh *ssh, const char *method)
+               error_f("cannot decode key: %s", pkalg);
+               goto done;
+       }
+-      if (key->type != pktype) {
+-              error_f("type mismatch for decoded key "
+-                  "(received %d, expected %d)", key->type, pktype);
++      if (key->type != pktype || (sshkey_type_plain(pktype) == KEY_ECDSA &&
++          sshkey_ecdsa_nid_from_name(pkalg) != key->ecdsa_nid)) {
++              error_f("key type mismatch for decoded key "
++                  "(received %s, expected %s)", sshkey_ssh_name(key), pkalg);
+               goto done;
+       }
+       if (auth2_key_already_used(authctxt, key)) {
+diff --git a/auth2-pubkeyfile.c b/auth2-pubkeyfile.c
+index 31e7481fb..869c8e055 100644
+--- a/auth2-pubkeyfile.c
++++ b/auth2-pubkeyfile.c
+@@ -1,4 +1,4 @@
+-/* $OpenBSD: auth2-pubkeyfile.c,v 1.4 2023/03/05 05:34:09 dtucker Exp $ */
++/* $OpenBSD: auth2-pubkeyfile.c,v 1.8 2026/04/02 07:48:13 djm Exp $ */
+ /*
+  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
+  * Copyright (c) 2010 Damien Miller.  All rights reserved.
+@@ -50,6 +50,7 @@
+ #include "authfile.h"
+ #include "match.h"
+ #include "ssherr.h"
++#include "xmalloc.h"
+ 
+ int
+ auth_authorise_keyopts(struct passwd *pw, struct sshauthopt *opts,
+@@ -146,20 +147,23 @@ auth_authorise_keyopts(struct passwd *pw, struct 
sshauthopt *opts,
+ static int
+ match_principals_option(const char *principal_list, struct sshkey_cert *cert)
+ {
+-      char *result;
++      char *list, *olist, *entry;
+       u_int i;
+ 
+-      /* XXX percent_expand() sequences for authorized_principals? */
+-
+-      for (i = 0; i < cert->nprincipals; i++) {
+-              if ((result = match_list(cert->principals[i],
+-                  principal_list, NULL)) != NULL) {
+-                      debug3("matched principal from key options \"%.100s\"",
+-                          result);
+-                      free(result);
+-                      return 1;
++      olist = list = xstrdup(principal_list);
++      for (;;) {
++              if ((entry = strsep(&list, ",")) == NULL || *entry == '\0')
++                      break;
++              for (i = 0; i < cert->nprincipals; i++) {
++                      if (strcmp(entry, cert->principals[i]) == 0) {
++                              debug3("matched principal from key i"
++                                  "options \"%.100s\"", entry);
++                              free(olist);
++                              return 1;
++                      }
+               }
+       }
++      free(olist);
+       return 0;
+ }
+ 
+diff --git a/sshconnect2.c b/sshconnect2.c
+index a5f92f04c..a296c9b8c 100644
+--- a/sshconnect2.c
++++ b/sshconnect2.c
+@@ -1,4 +1,4 @@
+-/* $OpenBSD: sshconnect2.c,v 1.371 2023/12/18 14:45:49 djm Exp $ */
++/* $OpenBSD: sshconnect2.c,v 1.385 2026/04/02 07:48:13 djm Exp $ */
+ /*
+  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
+  * Copyright (c) 2008 Damien Miller.  All rights reserved.
+@@ -91,6 +91,7 @@ extern Options options;
+ static char *xxx_host;
+ static struct sockaddr *xxx_hostaddr;
+ static const struct ssh_conn_info *xxx_conn_info;
++static int key_type_allowed(struct sshkey *, const char *);
+ 
+ static int
+ verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh)
+@@ -100,6 +101,10 @@ verify_host_key_callback(struct sshkey *hostkey, struct 
ssh *ssh)
+       if ((r = sshkey_check_rsa_length(hostkey,
+           options.required_rsa_size)) != 0)
+               fatal_r(r, "Bad server host key");
++      if (!key_type_allowed(hostkey, options.hostkeyalgorithms)) {
++              fatal("Server host key %s not in HostKeyAlgorithms",
++                  sshkey_ssh_name(hostkey));
++      }
+       if (verify_host_key(xxx_host, xxx_hostaddr, hostkey,
+           xxx_conn_info) != 0)
+               fatal("Host key verification failed.");
+@@ -1608,34 +1613,37 @@ load_identity_file(Identity *id)
+ }
+ 
+ static int
+-key_type_allowed_by_config(struct sshkey *key)
++key_type_allowed(struct sshkey *key, const char *allowlist)
+ {
+-      if (match_pattern_list(sshkey_ssh_name(key),
+-          options.pubkey_accepted_algos, 0) == 1)
++      if (match_pattern_list(sshkey_ssh_name(key), allowlist, 0) == 1)
+               return 1;
+ 
+       /* RSA keys/certs might be allowed by alternate signature types */
+       switch (key->type) {
+       case KEY_RSA:
+-              if (match_pattern_list("rsa-sha2-512",
+-                  options.pubkey_accepted_algos, 0) == 1)
++              if (match_pattern_list("rsa-sha2-512", allowlist, 0) == 1)
+                       return 1;
+-              if (match_pattern_list("rsa-sha2-256",
+-                  options.pubkey_accepted_algos, 0) == 1)
++              if (match_pattern_list("rsa-sha2-256", allowlist, 0) == 1)
+                       return 1;
+               break;
+       case KEY_RSA_CERT:
+               if (match_pattern_list("[email protected]",
+-                  options.pubkey_accepted_algos, 0) == 1)
++                  allowlist, 0) == 1)
+                       return 1;
+               if (match_pattern_list("[email protected]",
+-                  options.pubkey_accepted_algos, 0) == 1)
++                  allowlist, 0) == 1)
+                       return 1;
+               break;
+       }
+       return 0;
+ }
+ 
++static int
++key_type_allowed_by_config(struct sshkey *key)
++{
++      return key_type_allowed(key, options.pubkey_accepted_algos);
++}
++
+ /* obtain a list of keys from the agent */
+ static int
+ get_agent_identities(struct ssh *ssh, int *agent_fdp,
+-- 
+2.43.0
+
diff --git a/meta/recipes-connectivity/openssh/openssh_9.6p1.bb 
b/meta/recipes-connectivity/openssh/openssh_9.6p1.bb
index 3a9010a7a4..9267bbd2c9 100644
--- a/meta/recipes-connectivity/openssh/openssh_9.6p1.bb
+++ b/meta/recipes-connectivity/openssh/openssh_9.6p1.bb
@@ -35,6 +35,7 @@ SRC_URI = 
"http://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-${PV}.tar
            file://CVE-2025-61985.patch \
            file://CVE-2025-61984.patch \
            file://CVE-2026-35385.patch \
+           file://CVE-2026-35387.patch \
            "
 SRC_URI[sha256sum] = 
"910211c07255a8c5ad654391b40ee59800710dd8119dd5362de09385aa7a777c"
 
-- 
2.43.0

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