The official Twitter of an Attack on Titan manga publisher has made a statement about the manga's copyright infringement, see the publisher's statement below:
"Kodansha is taking strict measures against illegal uploads.
We are currently working to identify the root cause of the leaks. All illegal uploads are being discussed with the police. We hope everyone continues to enjoy our official products."
Attack on Titan is published in Bessatsu Shounen , the next issue of the magazine will be released on January 9th. In addition, the 33rd volume of the manga will be released on January 8th.
The author then revealed last month that he is about 2% short of completing his work.
Source: ANN