Possible NULL Dereference When Processing CMS KeyAgreeRecipientInfo

Issue summary: During processing of a crafted CMS EnvelopedData message

with KeyAgreeRecipientInfo a NULL pointer dereference can happen.

Impact summary: Applications that process attacker-controlled CMS data may

crash before authentication or cryptographic operations occur resulting in

Denial of Service.

When a CMS EnvelopedData message that uses KeyAgreeRecipientInfo is

processed, the optional parameters field of KeyEncryptionAlgorithmIdentifier

is examined without checking for its presence. This results in a NULL

pointer dereference if the field is missing.

Applications and services that call CMS_decrypt() on untrusted input

(e.g., S/MIME processing or CMS-based protocols) are vulnerable.

The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this

issue, as the affected code is outside the OpenSSL FIPS module boundary.