Package Instance

Buffer Overflow
In order to decrypt SM2 encrypted data an application is expected to call the API function `EVP_PKEY_decrypt()`. Typically an application will call this function twice. The first time, on entry, the `out` parameter can be NULL and, on exit, the `outlen` parameter is populated with the buffer size required to hold the decrypted plaintext. The application can then allocate a sufficiently sized buffer and call `EVP_PKEY_decrypt()` again, but this time passing a non-NULL value for the `out` parameter. A bug in the implementation of the SM2 decryption code means that the calculation of the buffer size required to hold the plaintext returned by the first call to `EVP_PKEY_decrypt()` can be smaller than the actual size required by the second call. This can lead to a buffer overflow when `EVP_PKEY_decrypt()` is called by the application a second time with a buffer that is too small. A malicious attacker who is able present SM2 content for decryption to an application could cause attacker chosen data to overflow the buffer by up to a maximum of bytes altering the contents of other data held after the buffer, possibly changing application behaviour or causing the application to crash. The location of the buffer is application dependent but is typically heap allocated.

A vulnerability in OpenSSL might allow remote attackers to cause a
    Denial of Service condition.

Multiple vulnerabilities have been found in OpenSSL, the worst of
    which might allow attackers to access sensitive information.

Improper Certificate Validation
Applications that use a non-default option when verifying certificates may be vulnerable to an attack from a malicious CA to circumvent certain checks. Invalid certificate policies in leaf certificates are silently ignored by OpenSSL and other certificate policy checks are skipped for that certificate. A malicious CA could use this to deliberately assert invalid certificate policies in order to circumvent policy checking on the certificate altogether. Policy processing is disabled by default but can be enabled by passing the `-policy' argument to the command line utilities or by calling the `X509_VERIFY_PARAM_set1_policies()' function.