In verify_emsa_pkcs1_signature() in gmp_rsa_public_key.c in the gmp plugin in strongSwan 4.x and 5.x before 5.7.0, the RSA implementation based on GMP does not reject excess data after the encoded algorithm OID during PKCS#1 v1.5 signature verification. Similar to the flaw in the same version of strongSwan regarding digestAlgorithm.parameters, a remote attacker can forge signatures when small public exponents are being used, which could lead to impersonation when only an RSA signature is used for IKEv2 authentication.
The product does not verify, or incorrectly verifies, the cryptographic signature for data.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Strongswan | Strongswan | 4.0.0 (including) | 4.6.4 (including) |
| Strongswan | Strongswan | 5.0.0 (including) | 5.7.0 (excluding) |
| Strongswan | Ubuntu | bionic | * |
| Strongswan | Ubuntu | devel | * |
| Strongswan | Ubuntu | trusty | * |
| Strongswan | Ubuntu | xenial | * |