CVE-2023-5363

Issue summary: A bug has been identified in the processing of key and

initialisation vector (IV) lengths. This can lead to potential truncation

or overruns during the initialisation of some symmetric ciphers.

Impact summary: A truncation in the IV can result in non-uniqueness,

which could result in loss of confidentiality for some cipher modes.

When calling EVP_EncryptInit_ex2(), EVP_DecryptInit_ex2() or

EVP_CipherInit_ex2() the provided OSSL_PARAM array is processed after

the key and IV have been established. Any alterations to the key length,

via the "keylen" parameter or the IV length, via the "ivlen" parameter,

within the OSSL_PARAM array will not take effect as intended, potentially

causing truncation or overreading of these values. The following ciphers

and cipher modes are impacted: RC2, RC4, RC5, CCM, GCM and OCB.

For the CCM, GCM and OCB cipher modes, truncation of the IV can result in

loss of confidentiality. For example, when following NIST's SP 800-38D

section 8.2.1 guidance for constructing a deterministic IV for AES in

GCM mode, truncation of the counter portion could lead to IV reuse.

Both truncations and overruns of the key and overruns of the IV will

produce incorrect results and could, in some cases, trigger a memory

exception. However, these issues are not currently assessed as security

critical.

Changing the key and/or IV lengths is not considered to be a common operation

and the vulnerable API was recently introduced. Furthermore it is likely that

application developers will have spotted this problem during testing since

decryption would fail unless both peers in the communication were similarly

vulnerable. For these reasons we expect the probability of an application being

vulnerable to this to be quite low. However if an application is vulnerable then

this issue is considered very serious. For these reasons we have assessed this

issue as Moderate severity overall.

The OpenSSL SSL/TLS implementation is not affected by this issue.

The OpenSSL 3.0 and 3.1 FIPS providers are not affected by this because

the issue lies outside of the FIPS provider boundary.

OpenSSL 3.1 and 3.0 are vulnerable to this issue.