int ssl3_send_server_certificate(SSL *s)
{
    CERT_PKEY *cpk;

    if (s->state == SSL3_ST_SW_CERT_A) {
        cpk = ssl_get_server_send_pkey(s);
        if (cpk == NULL) {
            /* VRS: allow null cert if auth == KRB5 */
            if ((s->s3->tmp.new_cipher->algorithm_auth != SSL_aKRB5) ||
                (s->s3->tmp.new_cipher->algorithm_mkey & SSL_kKRB5)) {
                SSLerr(SSL_F_SSL3_SEND_SERVER_CERTIFICATE,
                       ERR_R_INTERNAL_ERROR);
                s->state = SSL_ST_ERR;
                return (0);
            }
        }

        if (!ssl3_output_cert_chain(s, cpk)) {
            SSLerr(SSL_F_SSL3_SEND_SERVER_CERTIFICATE, ERR_R_INTERNAL_ERROR);
            s->state = SSL_ST_ERR;
            return (0);
        }
        s->state = SSL3_ST_SW_CERT_B;
    }

    /* SSL3_ST_SW_CERT_B */
    return ssl_do_write(s);
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.