[OE-core][scarthgap][PATCH 7/7] gnutls: Fix CVE-2026-5260

[hsimeliere.opensource@witekio.com]

From: "Hugo SIMELIERE (Schneider Electric)" <hsimeliere.opensource@witekio.com>

Pick patches from [1] and [2] as mentioned in Debian report in [3].

[1] https://gitlab.com/gnutls/gnutls/-/commit/77228f2d1ac207d2f894e5a168fbb47e5378e42f
[2] https://gitlab.com/gnutls/gnutls/-/commit/cf6bdc5e4df49e5583d3fb4d2296779785f10683
[3] https://security-tracker.debian.org/tracker/CVE-2026-5260

Signed-off-by: Hugo SIMELIERE (Schneider Electric) <hsimeliere.opensource@witekio.com>
Reviewed-by: Bruno VERNAY <bruno.vernay@se.com>
---
 .../gnutls/gnutls/CVE-2026-5260-1.patch       | 78 +++++++++++++++++++
 .../gnutls/gnutls/CVE-2026-5260-2.patch       | 40 ++++++++++
 meta/recipes-support/gnutls/gnutls_3.8.4.bb   |  2 +
 3 files changed, 120 insertions(+)
 create mode 100644 meta/recipes-support/gnutls/gnutls/CVE-2026-5260-1.patch
 create mode 100644 meta/recipes-support/gnutls/gnutls/CVE-2026-5260-2.patch

diff --git a/meta/recipes-support/gnutls/gnutls/CVE-2026-5260-1.patch b/meta/recipes-support/gnutls/gnutls/CVE-2026-5260-1.patch
new file mode 100644
index 0000000000..060440e8b7
--- /dev/null
+++ b/meta/recipes-support/gnutls/gnutls/CVE-2026-5260-1.patch
@@ -0,0 +1,78 @@
+From a39a21031f9e56d31747b060f83fb49d1a77f0c5 Mon Sep 17 00:00:00 2001
+From: Alexander Sosedkin <asosedkin@redhat.com>
+Date: Mon, 30 Mar 2026 17:31:07 +0200
+Subject: [PATCH 1/2] lib/auth/rsa: check that ciphertext matches the modulus
+ size
+
+A client sending extremely short premaster secret as part of an
+RSA key exchange could've theoretically triggered a short heap overread
+to nowhere when the RSA key was backed with a PKCS#11 token.
+With this fix, the internal decryption function will not be called
+with an mismatching plaintext length specified, avoiding the overread.
+
+Reported-by: Joshua Rogers of AISLE Research Team <joshua@joshua.hu>
+Fixes: #1814
+Fixes: CVE-2026-5260
+Fixes: GNUTLS-SA-2026-04-29-10
+CVSS: 5.9 Medium CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
+
+CVE: CVE-2026-5260
+Upstream-Status: Backport [https://gitlab.com/gnutls/gnutls/-/commit/77228f2d1ac207d2f894e5a168fbb47e5378e42f]
+
+Signed-off-by: Alexander Sosedkin <asosedkin@redhat.com>
+(cherry picked from commit 77228f2d1ac207d2f894e5a168fbb47e5378e42f)
+Signed-off-by: Hugo SIMELIERE (Schneider Electric) <hsimeliere.opensource@witekio.com>
+---
+ lib/auth/rsa.c     | 5 +++++
+ lib/auth/rsa_psk.c | 5 +++++
+ 2 files changed, 10 insertions(+)
+
+diff --git a/lib/auth/rsa.c b/lib/auth/rsa.c
+index b5ecc092f..24c1649be 100644
+--- a/lib/auth/rsa.c
++++ b/lib/auth/rsa.c
+@@ -158,6 +158,7 @@ static int proc_rsa_client_kx(gnutls_session_t session, uint8_t *data,
+ 	int ret, dsize;
+ 	ssize_t data_size = _data_size;
+ 	volatile uint8_t ver_maj, ver_min;
++	unsigned int key_bits;
+ 
+ #ifdef ENABLE_SSL3
+ 	if (get_num_version(session) == GNUTLS_SSL3) {
+@@ -180,6 +181,10 @@ static int proc_rsa_client_kx(gnutls_session_t session, uint8_t *data,
+ 		}
+ 		ciphertext.size = dsize;
+ 	}
++	gnutls_privkey_get_pk_algorithm(session->internals.selected_key,
++					&key_bits);
++	if (ciphertext.size != (key_bits + 7) / 8)
++		return gnutls_assert_val(GNUTLS_E_DECRYPTION_FAILED);
+ 
+ 	ver_maj = _gnutls_get_adv_version_major(session);
+ 	ver_min = _gnutls_get_adv_version_minor(session);
+diff --git a/lib/auth/rsa_psk.c b/lib/auth/rsa_psk.c
+index a14de467a..a1da1b320 100644
+--- a/lib/auth/rsa_psk.c
++++ b/lib/auth/rsa_psk.c
+@@ -257,6 +257,7 @@ static int _gnutls_proc_rsa_psk_client_kx(gnutls_session_t session,
+ 	ssize_t data_size = _data_size;
+ 	gnutls_psk_server_credentials_t cred;
+ 	volatile uint8_t ver_maj, ver_min;
++	unsigned int rsa_key_bits;
+ 
+ 	cred = (gnutls_psk_server_credentials_t)_gnutls_get_cred(
+ 		session, GNUTLS_CRD_PSK);
+@@ -313,6 +314,10 @@ static int _gnutls_proc_rsa_psk_client_kx(gnutls_session_t session,
+ 		return GNUTLS_E_UNEXPECTED_PACKET_LENGTH;
+ 	}
+ 	ciphertext.size = dsize;
++	gnutls_privkey_get_pk_algorithm(session->internals.selected_key,
++					&rsa_key_bits);
++	if (ciphertext.size != (rsa_key_bits + 7) / 8)
++		return gnutls_assert_val(GNUTLS_E_DECRYPTION_FAILED);
+ 
+ 	ver_maj = _gnutls_get_adv_version_major(session);
+ 	ver_min = _gnutls_get_adv_version_minor(session);
+-- 
+2.43.0
+
diff --git a/meta/recipes-support/gnutls/gnutls/CVE-2026-5260-2.patch b/meta/recipes-support/gnutls/gnutls/CVE-2026-5260-2.patch
new file mode 100644
index 0000000000..32181e45da
--- /dev/null
+++ b/meta/recipes-support/gnutls/gnutls/CVE-2026-5260-2.patch
@@ -0,0 +1,40 @@
+From 9b58b5237713d2189192aa8591b337787ee2edff Mon Sep 17 00:00:00 2001
+From: Alexander Sosedkin <asosedkin@redhat.com>
+Date: Mon, 30 Mar 2026 17:46:40 +0200
+Subject: [PATCH 2/2] lib/pkcs11_privkey: guard against overreading on short
+ ciphertexts
+
+This is an alternative fix for the callee side.
+
+Reported-by: Joshua Rogers of AISLE Research Team <joshua@joshua.hu>
+Fixes: #1814
+Fixes: CVE-2026-5260
+Fixes: GNUTLS-SA-2026-04-29-10
+CVSS: 5.9 Medium CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
+
+CVE: CVE-2026-5260
+Upstream-Status: Backport [https://gitlab.com/gnutls/gnutls/-/commit/cf6bdc5e4df49e5583d3fb4d2296779785f10683]
+
+Signed-off-by: Alexander Sosedkin <asosedkin@redhat.com>
+(cherry picked from commit cf6bdc5e4df49e5583d3fb4d2296779785f10683)
+Signed-off-by: Hugo SIMELIERE (Schneider Electric) <hsimeliere.opensource@witekio.com>
+---
+ lib/pkcs11_privkey.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/lib/pkcs11_privkey.c b/lib/pkcs11_privkey.c
+index 5093a6d56..369b034a6 100644
+--- a/lib/pkcs11_privkey.c
++++ b/lib/pkcs11_privkey.c
+@@ -826,7 +826,7 @@ int _gnutls_pkcs11_privkey_decrypt_data2(gnutls_pkcs11_privkey_t key,
+ 	if (ret != 0)
+ 		return gnutls_assert_val(GNUTLS_E_LOCKING_ERROR);
+ 
+-	buffer = gnutls_malloc(siglen);
++	buffer = gnutls_malloc(MAX((size_t)siglen, plaintext_size));
+ 	if (!buffer) {
+ 		gnutls_assert();
+ 		return GNUTLS_E_MEMORY_ERROR;
+-- 
+2.43.0
+
diff --git a/meta/recipes-support/gnutls/gnutls_3.8.4.bb b/meta/recipes-support/gnutls/gnutls_3.8.4.bb
index 0b3abb827c..a4a6a5fe21 100644
--- a/meta/recipes-support/gnutls/gnutls_3.8.4.bb
+++ b/meta/recipes-support/gnutls/gnutls_3.8.4.bb
@@ -51,6 +51,8 @@ SRC_URI = "https://www.gnupg.org/ftp/gcrypt/gnutls/v${SHRT_VER}/gnutls-${PV}.tar
            file://CVE-2026-42015.patch \
            file://CVE-2026-42014.patch \
            file://CVE-2026-42010.patch \
+           file://CVE-2026-5260-1.patch \
+           file://CVE-2026-5260-2.patch \
            "
 
 SRC_URI[sha256sum] = "2bea4e154794f3f00180fa2a5c51fe8b005ac7a31cd58bd44cdfa7f36ebc3a9b"
-- 
2.43.0