[wrynose][PATCH 2/2] gnupg: fix CVE-2026-57062

[Roland Kovacs <roland.kovacs@est.tech>]

CMS (Cryptographic Message Syntax) parsing in gpgsm in GnuPG through 2.5.20
mishandles the CMS format for AES-GCM because aes-ICVlen is supposed to be
12 bytes but 4 bytes is accepted.

Signed-off-by: Roland Kovacs <roland.kovacs@est.tech>
---
 .../gnupg/gnupg/CVE-2026-57062.patch          | 43 +++++++++++++++++++
 meta/recipes-support/gnupg/gnupg_2.5.20.bb    |  1 +
 2 files changed, 44 insertions(+)
 create mode 100644 meta/recipes-support/gnupg/gnupg/CVE-2026-57062.patch

diff --git a/meta/recipes-support/gnupg/gnupg/CVE-2026-57062.patch b/meta/recipes-support/gnupg/gnupg/CVE-2026-57062.patch
new file mode 100644
index 0000000000..f298b6e9a8
--- /dev/null
+++ b/meta/recipes-support/gnupg/gnupg/CVE-2026-57062.patch
@@ -0,0 +1,43 @@
+From d586f50ee849c8cbeaea47b50c64446c1becbf9b Mon Sep 17 00:00:00 2001
+From: Werner Koch <wk@gnupg.org>
+Date: Thu, 18 Jun 2026 10:51:34 +0200
+Subject: [PATCH] gpgsm: Require a minimum tag length for GCM decryption.
+
+* sm/decrypt.c (gpgsm_decrypt): Require a minimum authtaglen.
+--
+
+Reported-by: Thai Duong <thai@calif.io>
+This is similar to OpenSSL's
+CVE-id: CVE-2026-34182
+
+CVE: CVE-2026-57062
+Upstream-Status: Backport [https://github.com/gpg/gnupg/commit/4c7e68cf3d335328821bdbb70db309a60d0e4fd4]
+
+Signed-off-by: Roland Kovacs <roland.kovacs@est.tech>
+---
+ sm/decrypt.c | 9 ++++++++-
+ 1 file changed, 8 insertions(+), 1 deletion(-)
+
+diff --git a/sm/decrypt.c b/sm/decrypt.c
+index 20fb96060..92a33c6e6 100644
+--- a/sm/decrypt.c
++++ b/sm/decrypt.c
+@@ -1447,7 +1447,14 @@ gpgsm_decrypt (ctrl_t ctrl, estream_t in_fp, estream_t out_fp)
+                 }
+               if (DBG_CRYPTO)
+                 log_printhex (authtag, authtaglen, "Authtag ...:");
+-              rc = gcry_cipher_checktag (dfparm.hd, authtag, authtaglen);
++              if (authtaglen < 12)
++                {
++                  log_info ("authentication tag is too short (%zu octets)\n",
++                            authtaglen);
++                  rc = gpg_error (GPG_ERR_CHECKSUM);
++                }
++              else
++                rc = gcry_cipher_checktag (dfparm.hd, authtag, authtaglen);
+               xfree (authtag);
+               if (rc)
+                 log_error ("data is not authentic: %s\n", gpg_strerror (rc));
+-- 
+2.34.1
+
diff --git a/meta/recipes-support/gnupg/gnupg_2.5.20.bb b/meta/recipes-support/gnupg/gnupg_2.5.20.bb
index a1a50e2384..e373265c48 100644
--- a/meta/recipes-support/gnupg/gnupg_2.5.20.bb
+++ b/meta/recipes-support/gnupg/gnupg_2.5.20.bb
@@ -20,6 +20,7 @@ SRCREV = "343d0cb8910441aa44c56ce8673a78e137040c87"
 SRC_URI = "${GNUPG_MIRROR}/${BPN}/${BPN}-${PV}.tar.bz2 \
            file://0002-use-pkgconfig-instead-of-npth-config.patch \
            file://0001-Woverride-init-is-not-needed-with-gcc-9.patch \
+           file://CVE-2026-57062.patch \
            "
 SRC_URI:append:class-native = " file://0001-configure.ac-use-a-custom-value-for-the-location-of-.patch \
                                 file://relocate.patch"
-- 
2.34.1