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[AutoPR- Security] Patch libssh for CVE-2025-8277 [LOW] (microsoft#14655)
Co-authored-by: Archana Shettigar <[email protected]>
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‎SPECS/libssh/CVE-2025-8277.patch‎

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From b1207905f9194d5bfa17393e605987f158e9448b Mon Sep 17 00:00:00 2001
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From: AllSpark <[email protected]>
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Date: Thu, 11 Sep 2025 16:00:02 +0000
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Subject: [PATCH] CVE-2025-8277: Avoid leaking ECDH keys and free previous
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DH/ECDH contexts; adjust packet filter for DH-GEX guess; free previously
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allocated pubkeys
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Signed-off-by: Azure Linux Security Servicing Account <[email protected]>
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Upstream-reference: AI Backport of https://git.libssh.org/projects/libssh.git/patch/?id=1c763e29d138db87665e98983f468d2dd0f286c1 https://git.libssh.org/projects/libssh.git/patch/?id=8e4d67aa9eda455bfad9ac610e54b7a548d0aa08 https://git.libssh.org/projects/libssh.git/patch/?id=266174a6d36687b65cf90174f06af90b8b27c65f https://git.libssh.org/projects/libssh.git/patch/?id=87db2659ec608a977a63eea529f17b9168388d73
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---
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src/dh_crypto.c | 5 +++++
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src/dh_key.c | 5 +++++
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src/ecdh_crypto.c | 11 +++++++++++
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src/ecdh_gcrypt.c | 8 ++++++++
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src/ecdh_mbedcrypto.c | 7 +++++++
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src/packet.c | 2 ++
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src/wrapper.c | 10 +++++++++-
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7 files changed, 47 insertions(+), 1 deletion(-)
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diff --git a/src/dh_crypto.c b/src/dh_crypto.c
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index 9ff7ad3..325c568 100644
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--- a/src/dh_crypto.c
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+++ b/src/dh_crypto.c
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@@ -407,6 +407,11 @@ int ssh_dh_init_common(struct ssh_crypto_struct *crypto)
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struct dh_ctx *ctx = NULL;
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int rc;
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+ /* Cleanup any previously allocated dh_ctx */
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+ if (crypto->dh_ctx != NULL) {
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+ ssh_dh_cleanup(crypto);
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+ }
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+
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ctx = calloc(1, sizeof(*ctx));
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if (ctx == NULL) {
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return SSH_ERROR;
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diff --git a/src/dh_key.c b/src/dh_key.c
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index 20d24a3..d9743ce 100644
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--- a/src/dh_key.c
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+++ b/src/dh_key.c
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@@ -237,6 +237,11 @@ int ssh_dh_init_common(struct ssh_crypto_struct *crypto)
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struct dh_ctx *ctx = NULL;
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int rc;
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+ /* Cleanup any previously allocated dh_ctx */
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+ if (crypto->dh_ctx != NULL) {
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+ ssh_dh_cleanup(crypto);
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+ }
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+
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ctx = calloc(1, sizeof(*ctx));
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if (ctx == NULL) {
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return SSH_ERROR;
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diff --git a/src/ecdh_crypto.c b/src/ecdh_crypto.c
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index 069b137..8ad9bbf 100644
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--- a/src/ecdh_crypto.c
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+++ b/src/ecdh_crypto.c
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@@ -219,7 +219,18 @@ int ssh_client_ecdh_init(ssh_session session){
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return SSH_ERROR;
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}
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+ /* Free any previously allocated privkey #if OPENSSL_VERSION_NUMBER < 0x30000000L */
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+ if (session->next_crypto->ecdh_privkey != NULL) {
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+#if 1
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+ EC_KEY_free(session->next_crypto->ecdh_privkey);
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+#else
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+ EVP_PKEY_free(session->next_crypto->ecdh_privkey);
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+#endif
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+ session->next_crypto->ecdh_privkey = NULL;
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+ }
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+
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session->next_crypto->ecdh_privkey = key;
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+ ssh_string_free(session->next_crypto->ecdh_client_pubkey);
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session->next_crypto->ecdh_client_pubkey = client_pubkey;
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/* register the packet callbacks */
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diff --git a/src/ecdh_gcrypt.c b/src/ecdh_gcrypt.c
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index 3d9d426..918b0f5 100644
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--- a/src/ecdh_gcrypt.c
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+++ b/src/ecdh_gcrypt.c
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@@ -101,8 +101,16 @@ int ssh_client_ecdh_init(ssh_session session)
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goto out;
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}
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+ /* Free any previously allocated privkey */
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+ if (session->next_crypto->ecdh_privkey != NULL) {
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+ gcry_sexp_release(session->next_crypto->ecdh_privkey);
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+ session->next_crypto->ecdh_privkey = NULL;
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+ }
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+
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session->next_crypto->ecdh_privkey = key;
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key = NULL;
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+
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+ SSH_STRING_FREE(session->next_crypto->ecdh_client_pubkey);
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session->next_crypto->ecdh_client_pubkey = client_pubkey;
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client_pubkey = NULL;
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diff --git a/src/ecdh_mbedcrypto.c b/src/ecdh_mbedcrypto.c
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index dda7392..351aa65 100644
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--- a/src/ecdh_mbedcrypto.c
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+++ b/src/ecdh_mbedcrypto.c
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@@ -70,6 +70,12 @@ int ssh_client_ecdh_init(ssh_session session)
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return SSH_ERROR;
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}
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+ /* Free any previously allocated privkey */
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+ if (session->next_crypto->ecdh_privkey != NULL) {
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+ mbedtls_ecp_keypair_free(session->next_crypto->ecdh_privkey);
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+ SAFE_FREE(session->next_crypto->ecdh_privkey);
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+ }
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+
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session->next_crypto->ecdh_privkey = malloc(sizeof(mbedtls_ecp_keypair));
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if (session->next_crypto->ecdh_privkey == NULL) {
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return SSH_ERROR;
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@@ -110,6 +116,7 @@ int ssh_client_ecdh_init(ssh_session session)
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goto out;
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}
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+ SSH_STRING_FREE(session->next_crypto->ecdh_client_pubkey);
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session->next_crypto->ecdh_client_pubkey = client_pubkey;
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client_pubkey = NULL;
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diff --git a/src/packet.c b/src/packet.c
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index ea73f9a..dfb8b01 100644
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--- a/src/packet.c
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+++ b/src/packet.c
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@@ -294,6 +294,7 @@ static enum ssh_packet_filter_result_e ssh_packet_incoming_filter(ssh_session se
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* or session_state == SSH_SESSION_STATE_INITIAL_KEX
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* - dh_handshake_state == DH_STATE_INIT
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* or dh_handshake_state == DH_STATE_INIT_SENT (re-exchange)
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+ * or dh_handshake_state == DH_STATE_REQUEST_SENT (dh-gex)
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* or dh_handshake_state == DH_STATE_FINISHED (re-exchange)
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*
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* Transitions:
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@@ -313,6 +314,7 @@ static enum ssh_packet_filter_result_e ssh_packet_incoming_filter(ssh_session se
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if ((session->dh_handshake_state != DH_STATE_INIT) &&
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(session->dh_handshake_state != DH_STATE_INIT_SENT) &&
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+ (session->dh_handshake_state != DH_STATE_REQUEST_SENT) &&
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(session->dh_handshake_state != DH_STATE_FINISHED))
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{
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rc = SSH_PACKET_DENIED;
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diff --git a/src/wrapper.c b/src/wrapper.c
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index d317dc4..1f8cf84 100644
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--- a/src/wrapper.c
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+++ b/src/wrapper.c
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@@ -190,9 +190,17 @@ void crypto_free(struct ssh_crypto_struct *crypto)
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#endif /* OPENSSL_VERSION_NUMBER */
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#elif defined HAVE_GCRYPT_ECC
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gcry_sexp_release(crypto->ecdh_privkey);
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-#endif
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+#elif defined HAVE_LIBMBEDCRYPTO
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+ mbedtls_ecp_keypair_free(crypto->ecdh_privkey);
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+ SAFE_FREE(crypto->ecdh_privkey);
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+#endif /* HAVE_LIBGCRYPT */
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crypto->ecdh_privkey = NULL;
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}
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+#endif
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+#ifdef HAVE_LIBCRYPTO
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+ EVP_PKEY_free(crypto->curve25519_privkey);
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+#elif defined(HAVE_GCRYPT_CURVE25519)
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+ gcry_sexp_release(crypto->curve25519_privkey);
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#endif
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SAFE_FREE(crypto->dh_server_signature);
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if (crypto->session_id != NULL) {
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--
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2.45.4
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‎SPECS/libssh/libssh.spec‎

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@@ -2,7 +2,7 @@ Vendor: Microsoft Corporation
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Distribution: Azure Linux
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Name: libssh
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Version: 0.10.6
5-
Release: 3%{?dist}
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Release: 4%{?dist}
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Summary: A library implementing the SSH protocol
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License: LGPLv2+
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URL: http://www.libssh.org
@@ -17,6 +17,7 @@ Patch1: CVE-2025-5372.patch
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Patch2: CVE-2025-5351.patch
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Patch3: CVE-2025-5318.patch
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Patch4: CVE-2025-4878.patch
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Patch5: CVE-2025-8277.patch
2021

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BuildRequires: cmake
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BuildRequires: gcc-c++
@@ -150,6 +151,9 @@ popd
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%attr(0644,root,root) %config(noreplace) %{_sysconfdir}/libssh/libssh_server.config
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%changelog
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* Thu Sep 11 2025 Azure Linux Security Servicing Account <[email protected]> - 0.10.6-4
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- Patch for CVE-2025-8277
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* Thu Jul 24 2025 Jyoti Kanase <[email protected]> - 0.10.6-3
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- Patch for CVE-2025-4878
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