[Buildroot] [PATCH v2 4/5] package/libssh2: fix CVE-2026-66034

[Stefan Mueller via buildroot <buildroot@buildroot.org>]

From: Stefan Müller <stefan.mueller@rey-technology.com>

Backport the fix for CVE-2026-66034.

The publickey subsystem does not sufficiently validate the length of a
server-controlled comment field. A malformed response can therefore
cause an out-of-bounds read.

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

Signed-off-by: Stefan Müller <stefan.mueller@rey-technology.com>
---
Backport to: 2025.02.x
---
 ...009-publickey-fix-potential-OOB-read.patch | 35 +++++++++++++++++++
 package/libssh2/libssh2.mk                    |  3 ++
 2 files changed, 38 insertions(+)
 create mode 100644 package/libssh2/0009-publickey-fix-potential-OOB-read.patch

diff --git a/package/libssh2/0009-publickey-fix-potential-OOB-read.patch b/package/libssh2/0009-publickey-fix-potential-OOB-read.patch
new file mode 100644
index 0000000000..96b633f3d1
--- /dev/null
+++ b/package/libssh2/0009-publickey-fix-potential-OOB-read.patch
@@ -0,0 +1,35 @@
+From a13bb6c773f0d55ad1628cede57e99803cd898d9 Mon Sep 17 00:00:00 2001
+From: Viktor Szakats <commit@vsz.me>
+Date: Sat, 4 Jul 2026 11:19:49 +0200
+Subject: [PATCH] publickey: fix potential OOB read in
+ `libssh2_publickey_list_fetch()`
+
+Reported-by: Vladimir Eli Tokarev
+Fixes GHSA-w6g9-cpfp-22gc
+
+Closes #2202
+Forwarded: not-needed
+
+CVE: CVE-2026-66034
+Upstream: https://github.com/libssh2/libssh2/commit/a13bb6c773f0d55ad1628cede57e99803cd898d9
+Signed-off-by: Stefan Müller <stefan.mueller@rey-technology.com>
+---
+ src/publickey.c | 7 +++++++
+ 1 file changed, 7 insertions(+)
+
+--- a/src/publickey.c
++++ b/src/publickey.c
+@@ -988,6 +988,13 @@
+                 }
+
+                 if(comment_len) {
++                    if(pkey->listFetch_s + comment_len >
++                       pkey->listFetch_data + pkey->listFetch_data_len) {
++                        _libssh2_error(session, LIBSSH2_ERROR_BUFFER_TOO_SMALL,
++                                 "ListFetch data too short");
++                        goto err_exit;
++                    }
++
+                     list[keys].num_attrs = 1;
+                     list[keys].attrs =
+                         LIBSSH2_ALLOC(session,
diff --git a/package/libssh2/libssh2.mk b/package/libssh2/libssh2.mk
index a3c0b6a67f..4a4491f0f1 100644
--- a/package/libssh2/libssh2.mk
+++ b/package/libssh2/libssh2.mk
@@ -33,6 +33,9 @@ LIBSSH2_IGNORE_CVES += CVE-2026-66032
 # 0008-openssl-fix-AES-GCM-bounds-checks.patch
 LIBSSH2_IGNORE_CVES += CVE-2026-66033
 
+# 0009-publickey-fix-potential-OOB-read.patch
+LIBSSH2_IGNORE_CVES += CVE-2026-66034
+
 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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