diff --git a/src/curve25519_crypto.c b/src/curve25519_crypto.c
index b7e18411..3314f70e 100644
--- a/src/curve25519_crypto.c
+++ b/src/curve25519_crypto.c
@@ -79,6 +79,12 @@ int ssh_curve25519_init(ssh_session session)
         return SSH_ERROR;
     }
 
+    /* Free any previously allocated privkey */
+    if (session->next_crypto->curve25519_privkey != NULL) {
+        EVP_PKEY_free(session->next_crypto->curve25519_privkey);
+        session->next_crypto->curve25519_privkey = NULL;
+    }
+
     session->next_crypto->curve25519_privkey = pkey;
     pkey = NULL;
 
diff --git a/src/curve25519_gcrypt.c b/src/curve25519_gcrypt.c
index 5fae8cde..cd522a1d 100644
--- a/src/curve25519_gcrypt.c
+++ b/src/curve25519_gcrypt.c
@@ -89,6 +89,12 @@ int ssh_curve25519_init(ssh_session session)
 
     memcpy(*pubkey_loc, pubkey_data + 1, CURVE25519_PUBKEY_SIZE);
 
+    /* Free any previously allocated privkey */
+    if (session->next_crypto->curve25519_privkey != NULL) {
+        gcry_sexp_release(session->next_crypto->curve25519_privkey);
+        session->next_crypto->curve25519_privkey = NULL;
+    }
+
     /* Store the private key */
     session->next_crypto->curve25519_privkey = keypair_sexp;
     keypair_sexp = NULL;
diff --git a/src/dh_crypto.c b/src/dh_crypto.c
index d1241fd4..a646e856 100644
--- a/src/dh_crypto.c
+++ b/src/dh_crypto.c
@@ -407,6 +407,11 @@ int ssh_dh_init_common(struct ssh_crypto_struct *crypto)
     struct dh_ctx *ctx = NULL;
     int rc;
 
+    /* Cleanup any previously allocated dh_ctx */
+    if (crypto->dh_ctx != NULL) {
+        ssh_dh_cleanup(crypto);
+    }
+
     ctx = calloc(1, sizeof(*ctx));
     if (ctx == NULL) {
         return SSH_ERROR;
diff --git a/src/dh_key.c b/src/dh_key.c
index 20d24a31..d9743ceb 100644
--- a/src/dh_key.c
+++ b/src/dh_key.c
@@ -237,6 +237,11 @@ int ssh_dh_init_common(struct ssh_crypto_struct *crypto)
     struct dh_ctx *ctx = NULL;
     int rc;
 
+    /* Cleanup any previously allocated dh_ctx */
+    if (crypto->dh_ctx != NULL) {
+        ssh_dh_cleanup(crypto);
+    }
+
     ctx = calloc(1, sizeof(*ctx));
     if (ctx == NULL) {
         return SSH_ERROR;
diff --git a/src/ecdh_crypto.c b/src/ecdh_crypto.c
index 57c3dc89..a286804f 100644
--- a/src/ecdh_crypto.c
+++ b/src/ecdh_crypto.c
@@ -191,6 +191,17 @@ static ssh_string ssh_ecdh_generate(ssh_session session)
 #endif /* OPENSSL_VERSION_NUMBER */
         return NULL;
     }
+
+    /* Free any previously allocated privkey */
+    if (session->next_crypto->ecdh_privkey != NULL) {
+#if OPENSSL_VERSION_NUMBER < 0x30000000L
+        EC_KEY_free(session->next_crypto->ecdh_privkey);
+#else
+        EVP_PKEY_free(session->next_crypto->ecdh_privkey);
+#endif
+        session->next_crypto->ecdh_privkey = NULL;
+    }
+
     session->next_crypto->ecdh_privkey = key;
     return pubkey_string;
 }
diff --git a/src/ecdh_gcrypt.c b/src/ecdh_gcrypt.c
index a52ca84d..8eabfe18 100644
--- a/src/ecdh_gcrypt.c
+++ b/src/ecdh_gcrypt.c
@@ -101,6 +101,12 @@ int ssh_client_ecdh_init(ssh_session session)
         goto out;
     }
 
+    /* Free any previously allocated privkey */
+    if (session->next_crypto->ecdh_privkey != NULL) {
+        gcry_sexp_release(session->next_crypto->ecdh_privkey);
+        session->next_crypto->ecdh_privkey = NULL;
+    }
+
     session->next_crypto->ecdh_privkey = key;
     key = NULL;
     session->next_crypto->ecdh_client_pubkey = client_pubkey;
diff --git a/src/ecdh_mbedcrypto.c b/src/ecdh_mbedcrypto.c
index 1d9c8f36..d31bfcc7 100644
--- a/src/ecdh_mbedcrypto.c
+++ b/src/ecdh_mbedcrypto.c
@@ -70,6 +70,12 @@ int ssh_client_ecdh_init(ssh_session session)
         return SSH_ERROR;
     }
 
+    /* Free any previously allocated privkey */
+    if (session->next_crypto->ecdh_privkey != NULL) {
+        mbedtls_ecp_keypair_free(session->next_crypto->ecdh_privkey);
+        SAFE_FREE(session->next_crypto->ecdh_privkey);
+    }
+
     session->next_crypto->ecdh_privkey = malloc(sizeof(mbedtls_ecp_keypair));
     if (session->next_crypto->ecdh_privkey == NULL) {
         return SSH_ERROR;