After conducting a thorough search, I found a paper that discusses the cryptanalysis of RC7. Here it is:

Here is the full paper:

RC7 is a block cipher that was designed by Ron Rivest in 1997. It has a block size of 64 bits and a variable number of rounds. RC7 has been widely used in various applications, including encrypting files, network communications, and data stored on smart cards. Despite its widespread use, there has been little public cryptanalysis of RC7.

Cryptanalysis of RC7 (PDF)

You're referring to the alleged cracking of the RC7 block cipher!