Backport patch to fix CVE-2026-42012.

References:
  https://nvd.nist.gov/vuln/detail/CVE-2026-42012

Upstream fix:
  
https://gitlab.com/gnutls/gnutls/-/commit/8dcc6a1f48945997666ac9f10896819edd01a03b

Tested with ptest
Pre patches taken from upstream so CVE fix will land cleanly

Signed-off-by: Jakub Szczudlo <[email protected]>
---
 - delete unnedded lines from patches
 - correct patches to have also diff lines
 - document backport changes in CVE-2026-42012-pre2.patch

 .../gnutls/gnutls/CVE-2026-42012-pre1.patch   |  69 ++++++++
 .../gnutls/gnutls/CVE-2026-42012-pre2.patch   | 162 ++++++++++++++++++
 .../gnutls/gnutls/CVE-2026-42012-pre3.patch   | 129 ++++++++++++++
 .../gnutls/gnutls/CVE-2026-42012.patch        |  48 ++++++
 meta/recipes-support/gnutls/gnutls_3.8.4.bb   |   4 +
 5 files changed, 412 insertions(+)
 create mode 100644 meta/recipes-support/gnutls/gnutls/CVE-2026-42012-pre1.patch
 create mode 100644 meta/recipes-support/gnutls/gnutls/CVE-2026-42012-pre2.patch
 create mode 100644 meta/recipes-support/gnutls/gnutls/CVE-2026-42012-pre3.patch
 create mode 100644 meta/recipes-support/gnutls/gnutls/CVE-2026-42012.patch

diff --git a/meta/recipes-support/gnutls/gnutls/CVE-2026-42012-pre1.patch 
b/meta/recipes-support/gnutls/gnutls/CVE-2026-42012-pre1.patch
new file mode 100644
index 0000000000..9b2a5d16ca
--- /dev/null
+++ b/meta/recipes-support/gnutls/gnutls/CVE-2026-42012-pre1.patch
@@ -0,0 +1,69 @@
+From 6133fb459b74a9dcfa2d0ff010a4e03c56822d39 Mon Sep 17 00:00:00 2001
+From: Alexander Sosedkin <[email protected]>
+Date: Fri, 13 Mar 2026 17:00:03 +0100
+Subject: [PATCH] x509/hostname-verify: refactor and simplify CN fallback logic
+
+Signed-off-by: Alexander Sosedkin <[email protected]>
+CVE: CVE-2026-42012
+Upstream-Status: Backport 
[https://gitlab.com/gnutls/gnutls/-/commit/6133fb459b74a9dcfa2d0ff010a4e03c56822d39]
+
+Signed-off-by: Jakub Szczudlo <[email protected]>
+---
+ lib/x509/hostname-verify.c | 15 ++++++---------
+ 1 file changed, 6 insertions(+), 9 deletions(-)
+
+diff --git a/lib/x509/hostname-verify.c b/lib/x509/hostname-verify.c
+--- a/lib/x509/hostname-verify.c
++++ b/lib/x509/hostname-verify.c
+@@ -108,7 +108,7 @@ unsigned gnutls_x509_crt_check_ip(gnutls
+  * that we do not fallback to CN-ID if we encounter a supported name
+  * type.
+  */
+-#define IS_SAN_SUPPORTED(san) \
++#define PRECLUDES_CN_FALLBACK(san) \
+       (san == GNUTLS_SAN_DNSNAME || san == GNUTLS_SAN_IPADDRESS)
+ 
+ /**
+@@ -151,13 +151,12 @@ unsigned gnutls_x509_crt_check_hostname2
+ {
+       char dnsname[MAX_CN];
+       size_t dnsnamesize;
+-      int found_dnsname = 0;
+       int ret = 0;
+       int i = 0;
+       struct in_addr ipv4;
+       char *p = NULL;
+       char *a_hostname;
+-      unsigned have_other_addresses = 0;
++      bool cn_fallback_allowed = true;
+       gnutls_datum_t out;
+ 
+       /* check whether @hostname is an ip address */
+@@ -213,9 +212,10 @@ hostname_fallback:
+               ret = gnutls_x509_crt_get_subject_alt_name(cert, i, dnsname,
+                                                          &dnsnamesize, NULL);
+ 
+-              if (ret == GNUTLS_SAN_DNSNAME) {
+-                      found_dnsname = 1;
++              if (PRECLUDES_CN_FALLBACK(ret))
++                      cn_fallback_allowed = false;
+ 
++              if (ret == GNUTLS_SAN_DNSNAME) {
+                       if (memchr(dnsname, '\0', dnsnamesize)) {
+                               _gnutls_debug_log(
+                                       "certificate has %s with embedded null 
in name\n",
+@@ -236,13 +236,10 @@ hostname_fallback:
+                               ret = 1;
+                               goto cleanup;
+                       }
+-              } else {
+-                      if (IS_SAN_SUPPORTED(ret))
+-                              have_other_addresses = 1;
+               }
+       }
+ 
+-      if (!have_other_addresses && !found_dnsname &&
++      if (cn_fallback_allowed &&
+           _gnutls_check_key_purpose(cert, GNUTLS_KP_TLS_WWW_SERVER, 0) != 0) {
+               /* did not get the necessary extension, use CN instead, if the
+                * certificate would have been acceptable for a TLS WWW server 
purpose.
diff --git a/meta/recipes-support/gnutls/gnutls/CVE-2026-42012-pre2.patch 
b/meta/recipes-support/gnutls/gnutls/CVE-2026-42012-pre2.patch
new file mode 100644
index 0000000000..07a5f0127f
--- /dev/null
+++ b/meta/recipes-support/gnutls/gnutls/CVE-2026-42012-pre2.patch
@@ -0,0 +1,162 @@
+From 5cc003b9688378f6c7934b1df0aa147e80006be4 Mon Sep 17 00:00:00 2001
+From: Alexander Sosedkin <[email protected]>
+Date: Fri, 13 Mar 2026 17:41:33 +0100
+Subject: [PATCH] x509: add bare-bones awareness of SRV virtual SAN
+
+There's no support for constraints, no certtool support, no nothing.
+Just added what's easy to add because I needed a virtual SAN for them.
+
+Signed-off-by: Alexander Sosedkin <[email protected]>
+CVE: CVE-2026-42012
+Upstream-Status: Backport 
[https://gitlab.com/gnutls/gnutls/-/commit/5cc003b9688378f6c7934b1df0aa147e80006be4]
+
+Backport Changes:
+- common.h context updated for 3.8.4 (PKIX1_RSA_OAEP_P_SPECIFIED_OID).
+- virt-san.c: use _gnutls_steal_datum instead of upstream _gnutls_take_datum
+  (steal_datum comes from CVE-2026-42012-pre3).
+
+Signed-off-by: Jakub Szczudlo <[email protected]>
+---
+ lib/includes/gnutls/gnutls.h.in |  4 +++-
+ lib/x509/common.h               |  1 +
+ lib/x509/name_constraints.c     |  3 ++-
+ lib/x509/output.c               |  6 ++++++
+ lib/x509/virt-san.c             | 23 +++++++++++++++++++++++
+ lib/x509/x509.c                 |  3 ++-
+ 6 files changed, 37 insertions(+), 3 deletions(-)
+
+diff --git a/lib/includes/gnutls/gnutls.h.in b/lib/includes/gnutls/gnutls.h.in
+--- a/lib/includes/gnutls/gnutls.h.in
++++ b/lib/includes/gnutls/gnutls.h.in
+@@ -2646,6 +2646,7 @@ void gnutls_psk_set_server_params_functi
+  * @GNUTLS_SAN_OTHERNAME_XMPP: Virtual SAN, used by certain functions for 
convenience.
+  * @GNUTLS_SAN_OTHERNAME_KRB5PRINCIPAL: Virtual SAN, used by certain 
functions for convenience.
+  * @GNUTLS_SAN_OTHERNAME_MSUSERPRINCIPAL: Virtual SAN, used by certain 
functions for convenience.
++ * @GNUTLS_SAN_OTHERNAME_SRV: Virtual SAN, used by certain functions for 
convenience.
+  *
+  * Enumeration of different subject alternative names types.
+  */
+@@ -2663,7 +2664,8 @@ typedef enum gnutls_x509_subject_alt_nam
+          Used by gnutls_x509_crt_get_subject_alt_othername_oid.  */
+       GNUTLS_SAN_OTHERNAME_XMPP = 1000,
+       GNUTLS_SAN_OTHERNAME_KRB5PRINCIPAL,
+-      GNUTLS_SAN_OTHERNAME_MSUSERPRINCIPAL
++      GNUTLS_SAN_OTHERNAME_MSUSERPRINCIPAL,
++      GNUTLS_SAN_OTHERNAME_SRV
+ } gnutls_x509_subject_alt_name_t;
+ 
+ struct gnutls_openpgp_crt_int;
+diff --git a/lib/x509/common.h b/lib/x509/common.h
+--- a/lib/x509/common.h
++++ b/lib/x509/common.h
+@@ -107,6 +107,7 @@
+ #define XMPP_OID "1.3.6.1.5.5.7.8.5"
+ #define KRB5_PRINCIPAL_OID "1.3.6.1.5.2.2"
+ #define MSUSER_PRINCIPAL_NAME_OID "1.3.6.1.4.1.311.20.2.3"
++#define SRV_OID "1.3.6.1.5.5.7.8.7"
+ #define PKIX1_RSA_PSS_MGF1_OID "1.2.840.113549.1.1.8"
+ #define PKIX1_RSA_OAEP_P_SPECIFIED_OID "1.9"
+
+diff --git a/lib/x509/name_constraints.c b/lib/x509/name_constraints.c
+--- a/lib/x509/name_constraints.c
++++ b/lib/x509/name_constraints.c
+@@ -516,7 +516,8 @@ static int validate_name_constraints_nod
+       if (type != GNUTLS_SAN_DNSNAME && type != GNUTLS_SAN_RFC822NAME &&
+           type != GNUTLS_SAN_DN && type != GNUTLS_SAN_URI &&
+           type != GNUTLS_SAN_IPADDRESS &&
+-          type != GNUTLS_SAN_OTHERNAME_MSUSERPRINCIPAL) {
++          type != GNUTLS_SAN_OTHERNAME_MSUSERPRINCIPAL &&
++          type != GNUTLS_SAN_OTHERNAME_SRV) {
+               return gnutls_assert_val(GNUTLS_E_X509_UNKNOWN_SAN);
+       }
+ 
+diff --git a/lib/x509/output.c b/lib/x509/output.c
+--- a/lib/x509/output.c
++++ b/lib/x509/output.c
+@@ -121,6 +121,7 @@ static void print_name(gnutls_buffer_st
+       if ((type == GNUTLS_SAN_DNSNAME || type == GNUTLS_SAN_OTHERNAME_XMPP ||
+            type == GNUTLS_SAN_OTHERNAME_KRB5PRINCIPAL ||
+            type == GNUTLS_SAN_OTHERNAME_MSUSERPRINCIPAL ||
++           type == GNUTLS_SAN_OTHERNAME_SRV ||
+            type == GNUTLS_SAN_RFC822NAME || type == GNUTLS_SAN_URI) &&
+           sname != NULL && strlen(sname) != name->size) {
+               adds(str, _("warning: SAN contains an embedded NUL, "
+@@ -180,6 +181,11 @@ static void print_name(gnutls_buffer_st
+                    name->size, NON_NULL(name->data));
+               break;
+ 
++      case GNUTLS_SAN_OTHERNAME_SRV:
++              addf(str, _("%sSRVName: %.*s\n"), prefix, name->size,
++                   NON_NULL(name->data));
++              break;
++
+       default:
+               addf(str, _("%sUnknown name: "), prefix);
+               _gnutls_buffer_hexprint(str, name->data, name->size);
+diff --git a/lib/x509/virt-san.c b/lib/x509/virt-san.c
+--- a/lib/x509/virt-san.c
++++ b/lib/x509/virt-san.c
+@@ -45,6 +45,9 @@ static int san_othername_to_virtual(cons
+                        memcmp(oid, MSUSER_PRINCIPAL_NAME_OID,
+                               sizeof(MSUSER_PRINCIPAL_NAME_OID) - 1) == 0)
+                       return GNUTLS_SAN_OTHERNAME_MSUSERPRINCIPAL;
++              else if ((unsigned)size == (sizeof(SRV_OID) - 1) &&
++                       memcmp(oid, SRV_OID, sizeof(SRV_OID) - 1) == 0)
++                      return GNUTLS_SAN_OTHERNAME_SRV;
+       }
+ 
+       return GNUTLS_SAN_OTHERNAME;
+@@ -59,6 +62,8 @@ static const char *virtual_to_othername_
+               return KRB5_PRINCIPAL_OID;
+       case GNUTLS_SAN_OTHERNAME_MSUSERPRINCIPAL:
+               return MSUSER_PRINCIPAL_NAME_OID;
++      case GNUTLS_SAN_OTHERNAME_SRV:
++              return SRV_OID;
+       default:
+               return NULL;
+       }
+@@ -126,6 +131,15 @@ int _gnutls_alt_name_assign_virt_type(st
+                       name->type = GNUTLS_SAN_OTHERNAME;
+                       break;
+ 
++              case GNUTLS_SAN_OTHERNAME_SRV:
++                      ret = _gnutls_x509_encode_string(ASN1_ETYPE_IA5_STRING,
++                                                       san->data, san->size,
++                                                       &encoded);
++                      if (ret < 0)
++                              return gnutls_assert_val(ret);
++                      name->san = _gnutls_steal_datum(&encoded);
++                      break;
++
+               default:
+                       return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
+               }
+@@ -187,6 +201,15 @@ int gnutls_x509_othername_to_virtual(con
+                                                othername->data,
+                                                othername->size, virt, 0);
+               if (ret < 0) {
++                      gnutls_assert();
++                      return ret;
++              }
++              return 0;
++      case GNUTLS_SAN_OTHERNAME_SRV:
++              ret = _gnutls_x509_decode_string(ASN1_ETYPE_IA5_STRING,
++                                               othername->data,
++                                               othername->size, virt, 0);
++              if (ret < 0) {
+                       gnutls_assert();
+                       return ret;
+               }
+diff --git a/lib/x509/x509.c b/lib/x509/x509.c
+--- a/lib/x509/x509.c
++++ b/lib/x509/x509.c
+@@ -1554,7 +1554,8 @@ inline static int is_type_printable(int
+ {
+       if (type == GNUTLS_SAN_DNSNAME || type == GNUTLS_SAN_RFC822NAME ||
+           type == GNUTLS_SAN_URI || type == GNUTLS_SAN_OTHERNAME_XMPP ||
+-          type == GNUTLS_SAN_OTHERNAME || type == GNUTLS_SAN_REGISTERED_ID)
++          type == GNUTLS_SAN_OTHERNAME_SRV || type == GNUTLS_SAN_OTHERNAME ||
++          type == GNUTLS_SAN_REGISTERED_ID)
+               return 1;
+       else
+               return 0;
diff --git a/meta/recipes-support/gnutls/gnutls/CVE-2026-42012-pre3.patch 
b/meta/recipes-support/gnutls/gnutls/CVE-2026-42012-pre3.patch
new file mode 100644
index 0000000000..7ed76d0366
--- /dev/null
+++ b/meta/recipes-support/gnutls/gnutls/CVE-2026-42012-pre3.patch
@@ -0,0 +1,129 @@
+From 9f635788da50eb1285cae5c8d787b12bda01ae4d Mon Sep 17 00:00:00 2001
+From: Daiki Ueno <[email protected]>
+Date: Wed, 22 Jan 2025 07:45:46 +0900
+Subject: [PATCH] datum, mem, str: add helper functions to steal pointers
+
+This introduces 3 new inline functions, namely _gnutls_steal_datum,
+_gnutls_steal_buffer, and _gnutls_steal_pointer, to return a copy of
+data structure and reset the original pointer. Those would enable to
+return a populated data structure upon success; otherwise free the
+partially filled data structure in a single code path, e.g.,
+
+```c
+  gnutls_datum_t tmp_result = { NULL, 0 };
+
+  // Calculate tmp_result
+  ...
+  if (error)
+    goto cleanup;
+
+  // Propagate tmp_result to *result
+  *result = _gnutls_steal_datum(&tmp_result);
+
+cleanup:
+  _gnutls_free_datum(&tmp_result);
+  return ret;
+```
+
+Signed-off-by: Daiki Ueno <[email protected]>
+CVE: CVE-2026-42012
+Upstream-Status: Backport 
[https://gitlab.com/gnutls/gnutls/-/commit/9f635788da50eb1285cae5c8d787b12bda01ae4d]
+
+Signed-off-by: Jakub Szczudlo <[email protected]>
+---
+ lib/datum.h | 11 +++++++++++
+ lib/mem.h   |  9 +++++++++
+ lib/str.h   | 23 +++++++++++++++--------
+ 3 files changed, 35 insertions(+), 8 deletions(-)
+
+diff --git a/lib/datum.h b/lib/datum.h
+--- a/lib/datum.h
++++ b/lib/datum.h
+@@ -68,4 +68,15 @@ inline static ATTRIBUTE_NONNULL() void _
+       dat->size = 0;
+ }
+ 
++inline static ATTRIBUTE_NONNULL() gnutls_datum_t
++      _gnutls_steal_datum(gnutls_datum_t *src)
++{
++      gnutls_datum_t dst = *src;
++
++      src->data = NULL;
++      src->size = 0;
++
++      return dst;
++}
++
+ #endif /* GNUTLS_LIB_DATUM_H */
+diff --git a/lib/mem.h b/lib/mem.h
+--- a/lib/mem.h
++++ b/lib/mem.h
+@@ -33,6 +33,8 @@
+ #include <valgrind/memcheck.h>
+ #endif
+ 
++#include "attribute.h"
++
+ /* These realloc functions will return ptr if size==0, and will free
+  * the ptr if the new allocation failed.
+  */
+@@ -78,4 +80,11 @@ static inline void _gnutls_memory_mark_d
+ #endif
+ }
+ 
++static inline ATTRIBUTE_NONNULL() void *_gnutls_steal_pointer(void **src)
++{
++      void *dst = *src;
++      *src = NULL;
++      return dst;
++}
++
+ #endif /* GNUTLS_LIB_MEM_H */
+diff --git a/lib/str.h b/lib/str.h
+--- a/lib/str.h
++++ b/lib/str.h
+@@ -30,6 +30,7 @@
+ #include "datum.h"
+ #include <c-ctype.h>
+ #include "errors.h"
++#include "attribute.h"
+ 
+ #ifdef HAVE_DCGETTEXT
+ #include "gettext.h"
+@@ -97,6 +98,19 @@ inline static void _gnutls_buffer_reset(
+       buf->length = 0;
+ }
+ 
++inline static ATTRIBUTE_NONNULL() gnutls_buffer_st
++      _gnutls_steal_buffer(gnutls_buffer_st *src)
++{
++      gnutls_buffer_st dst = *src;
++
++      src->allocd = NULL;
++      src->data = NULL;
++      src->max_length = 0;
++      src->length = 0;
++
++      return dst;
++}
++
+ int _gnutls_buffer_resize(gnutls_buffer_st *, size_t new_size);
+ 
+ int _gnutls_buffer_append_str(gnutls_buffer_st *, const char *str);
+@@ -161,15 +175,8 @@ int _gnutls_buffer_append_escape(gnutls_
+                                size_t data_size, const char *invalid_chars);
+ int _gnutls_buffer_unescape(gnutls_buffer_st *dest);
+ 
+-#ifndef __attribute__
+-/* This feature is available in gcc versions 2.5 and later.  */
+-#if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 5)
+-#define __attribute__(Spec) /* empty */
+-#endif
+-#endif
+-
+ int _gnutls_buffer_append_printf(gnutls_buffer_st *dest, const char *fmt, ...)
+-      __attribute__((format(printf, 2, 3)));
++      ATTRIBUTE_FORMAT((printf, 2, 3));
+ 
+ void _gnutls_buffer_hexprint(gnutls_buffer_st *str, const void *data,
+                            size_t len);
diff --git a/meta/recipes-support/gnutls/gnutls/CVE-2026-42012.patch 
b/meta/recipes-support/gnutls/gnutls/CVE-2026-42012.patch
new file mode 100644
index 0000000000..1f43efc122
--- /dev/null
+++ b/meta/recipes-support/gnutls/gnutls/CVE-2026-42012.patch
@@ -0,0 +1,48 @@
+From 8dcc6a1f48945997666ac9f10896819edd01a03b Mon Sep 17 00:00:00 2001
+From: Alexander Sosedkin <[email protected]>
+Date: Fri, 13 Mar 2026 17:02:07 +0100
+Subject: [PATCH] x509/hostname-verify: make URI/SRV SAN preclude CN fallback
+
+URI/SRV SAN did not suppress CN fallback as required by RFC 6125 6.4.4:
+> a client MUST NOT seek a match for a reference identifier of CN-ID
+> if the presented identifiers include a DNS-ID, *SRV-ID*, *URI-ID*,
+> or any application-specific identifier types supported by the client.
+
+With this change, certificates containing URI or SRV SAN
+no longer pass DNS hostname checks via CN fallback
+to avoid potential misuse of such certificates
+beyond their original purpose.
+
+Reported-by: Oleh Konko <[email protected]>
+Fixes: #1802
+Fixes: CVE-2026-42012
+Fixes: GNUTLS-SA-2026-04-29-7
+CVSS: 6.5 Medium CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
+Signed-off-by: Alexander Sosedkin <[email protected]>
+CVE: CVE-2026-42012
+Upstream-Status: Backport 
[https://gitlab.com/gnutls/gnutls/-/commit/8dcc6a1f48945997666ac9f10896819edd01a03b]
+
+Signed-off-by: Jakub Szczudlo <[email protected]>
+---
+ lib/x509/hostname-verify.c | 5 +++--
+ 1 file changed, 3 insertions(+), 2 deletions(-)
+
+diff --git a/lib/x509/hostname-verify.c b/lib/x509/hostname-verify.c
+index e7597ad3b0..d989bb1abc 100644
+--- a/lib/x509/hostname-verify.c
++++ b/lib/x509/hostname-verify.c
+@@ -108,8 +108,9 @@ unsigned gnutls_x509_crt_check_ip(gnutls_x509_crt_t cert,
+  * that we do not fallback to CN-ID if we encounter a supported name
+  * type.
+  */
+-#define PRECLUDES_CN_FALLBACK(san) \
+-      (san == GNUTLS_SAN_DNSNAME || san == GNUTLS_SAN_IPADDRESS)
++#define PRECLUDES_CN_FALLBACK(san)                                   \
++      (san == GNUTLS_SAN_DNSNAME || san == GNUTLS_SAN_IPADDRESS || \
++       san == GNUTLS_SAN_URI || san == GNUTLS_SAN_OTHERNAME_SRV)
+ 
+ /**
+  * gnutls_x509_crt_check_hostname2:
+-- 
+GitLab
+
diff --git a/meta/recipes-support/gnutls/gnutls_3.8.4.bb 
b/meta/recipes-support/gnutls/gnutls_3.8.4.bb
index 641289be13..646cc350d9 100644
--- a/meta/recipes-support/gnutls/gnutls_3.8.4.bb
+++ b/meta/recipes-support/gnutls/gnutls_3.8.4.bb
@@ -52,6 +52,10 @@ SRC_URI = 
"https://www.gnupg.org/ftp/gcrypt/gnutls/v${SHRT_VER}/gnutls-${PV}.tar
            file://CVE-2026-33846.patch \
            file://CVE-2026-33845.patch \
            file://CVE-2026-5419.patch \
+           file://CVE-2026-42012-pre1.patch \
+           file://CVE-2026-42012-pre2.patch \
+           file://CVE-2026-42012-pre3.patch \
+           file://CVE-2026-42012.patch \
            "
 
 SRC_URI[sha256sum] = 
"2bea4e154794f3f00180fa2a5c51fe8b005ac7a31cd58bd44cdfa7f36ebc3a9b"
-- 
2.34.1

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