If you're using the Twitter app on an Android device then you could potentially be open to a cyber attack due to a vulnerability. This was due to the fact that somebody will be able to see nonpublic account information or even be able to control your account to a certain degree. For example, they may be able to send Direct Messages or even Tweet with your account!
This information was posted on Twitter's official privacy blog and was announced to the public via an official tweet. If you're on iOS, you don't have to worry - this is only affecting Android users.
The blog post stated that someone has inserted "malicious code into restricted storage areas of the Twitter app". It made it possible for bad apples to access information. They also said that they do not have evidence of the fact that the code was actually inserted in the wild. They also don't know if the vulnerability was exploited, but it definitely could of. Confused? But, they're still updating the app to stay on the safe side.
As well as this, people who could've been exposed to people trying to expose the vulnerability have been directly contacted either through email or Twitter itself. They have been given instructions on how to keep safe. To keep yourself safe, update the Android Twitter App ASAP!