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CVE-2025-8277: Fix memory leak of unused ephemeral key pair after client's wrong KEX guess

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Signed-off-by: Francesco Rollo <eferollo@gmail.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
This commit is contained in:
Francesco Rollo
2025-07-24 16:30:07 +03:00
committed by Jakub Jelen
parent 4310a696f2
commit ccff22d378
7 changed files with 45 additions and 0 deletions
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6
src/curve25519_crypto.c
View File

@@ -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;

6
src/curve25519_gcrypt.c
View File

@@ -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;

5
src/dh_crypto.c
View File

@@ -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;

5
src/dh_key.c
View File

@@ -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;

11
src/ecdh_crypto.c
View File

@@ -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;
}

6
src/ecdh_gcrypt.c
View File

@@ -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;

6
src/ecdh_mbedcrypto.c
View File

@@ -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;