[Buildroot] [PATCH v2 3/5] package/libssh2: fix CVE-2026-66033

From: Stefan Müller <[email protected]>

Backport the fix for CVE-2026-66033.

The OpenSSL AES-GCM cipher path lacks runtime bounds checks around the
input block size. A malformed packet can therefore lead to an
out-of-bounds read or write.

Use Debian's libssh2 1.11.1 backport of the upstream fix.

Signed-off-by: Stefan Müller <[email protected]>
---
Backport to: 2025.02.x
---
 ...08-openssl-fix-AES-GCM-bounds-checks.patch | 44 +++++++++++++++++++
 package/libssh2/libssh2.mk                    |  3 ++
 2 files changed, 47 insertions(+)
 create mode 100644 package/libssh2/0008-openssl-fix-AES-GCM-bounds-checks.patch

diff --git a/package/libssh2/0008-openssl-fix-AES-GCM-bounds-checks.patch b/package/libssh2/0008-openssl-fix-AES-GCM-bounds-checks.patch
new file mode 100644
index 0000000000..fdb78a1695
--- /dev/null
+++ b/package/libssh2/0008-openssl-fix-AES-GCM-bounds-checks.patch
@@ -0,0 +1,44 @@
+From a2ed82d40964bbc0d64cd717aa0a5a892117d2e6 Mon Sep 17 00:00:00 2001
+From: Viktor Szakats <[email protected]>
+Date: Thu, 23 Jul 2026 10:32:04 +0200
+Subject: [PATCH] openssl: fix potential OOB read/write with AES-GCM in
+ `ssh2_cipher_crypt()`
+
+By applying two bounds checks to non-debug builds.
+
+Reported-by: Vladimir Eli Tokarev
+Fixes GHSA-c4f7-cvfc-33j7
+Follow-up to 3c953c05d67eb1ebcfd3316f279f12c4b1d600b4 #797
+
+Closes #2401
+Forwarded: not-needed
+
+CVE: CVE-2026-66033
+Upstream: https://github.com/libssh2/libssh2/commit/a2ed82d40964bbc0d64cd717aa0a5a892117d2e6
+Signed-off-by: Stefan Müller <[email protected]>
+---
+ src/openssl.c | 10 ++++++----
+ 1 file changed, 6 insertions(+), 4 deletions(-)
+
+--- a/src/openssl.c
++++ b/src/openssl.c
+@@ -1042,13 +1042,15 @@
+     const int aadlen = (is_aesgcm && IS_FIRST(firstlast)) ? 4 : 0;
+     /* size of AT, if present */
+     const int authenticationtag = IS_LAST(firstlast) ? authlen : 0;
+-    /* length to encrypt */
+-    const int cryptlen = (unsigned int)blocksize - aadlen - authenticationtag;
++    unsigned int cryptlen; /* length to encrypt */
+
+     (void)algo;
+
+-    assert(blocksize <= sizeof(buf));
+-    assert(cryptlen >= 0);
++    if(blocksize > sizeof(buf) ||
++       blocksize < (size_t)(aadlen + authenticationtag))
++        return 1;
++
++    cryptlen = (unsigned int)blocksize - aadlen - authenticationtag;
+
+ #if LIBSSH2_AES_GCM
+     /* First block */
diff --git a/package/libssh2/libssh2.mk b/package/libssh2/libssh2.mk
index 583ed56c1c..a3c0b6a67f 100644
--- a/package/libssh2/libssh2.mk
+++ b/package/libssh2/libssh2.mk
@@ -30,6 +30,9 @@ LIBSSH2_IGNORE_CVES += CVE-2025-15661
 # 0007-sftp-prevent-dangling-pointer-after-free.patch
 LIBSSH2_IGNORE_CVES += CVE-2026-66032
 
+# 0008-openssl-fix-AES-GCM-bounds-checks.patch
+LIBSSH2_IGNORE_CVES += CVE-2026-66033
+
 ifeq ($(BR2_PACKAGE_LIBSSH2_MBEDTLS),y)
 LIBSSH2_DEPENDENCIES += mbedtls
 LIBSSH2_CONF_OPTS += --with-libmbedcrypto-prefix=$(STAGING_DIR)/usr \
-- 
2.25.1

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