libssh2: fix CVE-2026-66035

Reference:
https://nvd.nist.gov/vuln/detail/CVE-2026-66035
42e33d8157

libssh2 ptest results (qemux86-64):
  before: PASSED: 1 FAILED: 0 SKIPPED: 0
  after:  PASSED: 1 FAILED: 0 SKIPPED: 0

(From OE-Core rev: e0e829a80e9d8a736c41594c0fe7d4fddca9f0b4)

Signed-off-by: Jaipaul Cheernam <jaipaul.cheernam@est.tech>
Signed-off-by: Fabien Thomas <fabien.thomas@smile.fr>
Signed-off-by: Paul Barker <paul@pbarker.dev>

meta/recipes-support/libssh2/libssh2/CVE-2026-66035.patch

@@ -0,0 +1,56 @@
+From 6671019836476649792eea12868a370133be1abe Mon Sep 17 00:00:00 2001
+From: Viktor Szakats <commit@vsz.me>
+Date: Fri, 3 Jul 2026 18:22:55 +0200
+Subject: [PATCH] transport: fix potential heap overflow on ETM decrypt
+
+Reported-by: Vladimir Eli Tokarev
+Fixes GHSA-6c79-444r-wx26
+
+Closes #2198
+
+Backport adaptations:
+- The upstream fix uses SSH2_SAFEFREE() to safely release allocated
+  memory and reset the pointer. Since SSH2_SAFEFREE() is not available
+  in libssh2 1.11.1, replace its usage with the equivalent NULL check,
+  LIBSSH2_FREE(), and pointer reset sequence.
+- The upstream fix renames decrypt() to transport_decrypt(). Since this
+  rename is not present in libssh2 1.11.1, retain the original
+  decrypt() function name.
+
+CVE: CVE-2026-66035
+Upstream-Status: Backport [https://github.com/libssh2/libssh2/commit/42e33d81577ed4b95d4b4f6f845e5ee8efe5eeb4]
+Signed-off-by: Jaipaul Cheernam <jaipaul.cheernam@est.tech>
+---
+ src/transport.c | 12 +++++++++++-
+ 1 file changed, 11 insertions(+), 1 deletion(-)
+
+diff --git a/src/transport.c b/src/transport.c
+index d147505b..9f386e75 100644
+--- a/src/transport.c
++++ b/src/transport.c
+@@ -242,6 +242,17 @@ fullpacket(LIBSSH2_SESSION * session, int encrypted /* 1 or 0 */ )
+                 unsigned char *decrypt_buffer;
+                 int blocksize = session->remote.crypt->blocksize;
+ 
++                if(p->total_num < mac_len + 4 + (size_t)blocksize) {
++                    if(p->payload) {
++                        LIBSSH2_FREE(session, p->payload);
++                        p->payload = NULL;
++                    }
++                    return LIBSSH2_ERROR_DECRYPT;
++                }
++                decrypt_size = (ssize_t)(p->total_num - mac_len - 4);
++
++                first_block[0] = 0;
++
+                 rc = decrypt(session, p->payload + 4,
+                              first_block, blocksize, FIRST_BLOCK);
+                 if(rc) {
+@@ -249,7 +260,6 @@ fullpacket(LIBSSH2_SESSION * session, int encrypted /* 1 or 0 */ )
+                 }
+ 
+                 /* we need buffer for decrypt */
+-                decrypt_size = p->total_num - mac_len - 4;
+                 decrypt_buffer = LIBSSH2_ALLOC(session, decrypt_size);
+                 if(!decrypt_buffer) {
+                     return LIBSSH2_ERROR_ALLOC;

meta/recipes-support/libssh2/libssh2_1.11.1.bb

@@ -19,6 +19,7 @@ SRC_URI = "http://www.libssh2.org/download/${BP}.tar.gz \
            file://CVE-2026-66032.patch \
            file://CVE-2026-66033.patch \
            file://CVE-2026-66034.patch \
+           file://CVE-2026-66035.patch \
            "
 
 SRC_URI[sha256sum] = "d9ec76cbe34db98eec3539fe2c899d26b0c837cb3eb466a56b0f109cabf658f7"