Almost 5,000 disabled adults have been sexually abused in England in the past two years, figures show.
The NSPCC said information from 106 councils showing 4,748 reports of sex abuse against disabled adults is the "visible peak" of what could be a bigger problem.
People with learning difficulties were the victims of almost two thirds of reported incidents, the BBC found through Freedom of Information requests.
Jon Brown, the NSPCC's lead on tackling sexual abuse, said while these figures focus on adults, disabled young people can also be victims.
"We know with sexual abuse that many victims find it difficult to speak out," he told the BBC.
"We know from research that disabled children and young people are three or four times more likely to be abused and neglected than children and young people who are not disabled.
"Abusers are often very adept at identifying vulnerabilities. And, importantly, we know that it's less likely for children and young people to be believed as well."
The BBC's Victoria Derbyshire programme submitted requests for information to 152 councils with adult social services responsibilities.
The Local Government Association told the BBC that "keeping people safe, including people with learning disabilities, is one of the most important things councils do".
It said "councils work hard to ensure support is available when cases of abuse are referred".