Passage: In October 2017, security researchers found a vulnerability (known as ROCA) in the implementation of RSA keypair generation in a cryptographic library used by a large number of Infineon security chips. The vulnerability allows an attacker to reconstruct the private key by using the public key. All YubiKey 4, YubiKey 4C, and YubiKey 4 Nano devices within the revisions 4.2.6 to 4.3.4 were affected by this vulnerability. Yubico remedied this issue in all shipping YubiKey 4 devices by switching to a different key generation function and offered free replacements for any affected keys. The replacement offer ended on March 31, 2019. In some cases the issue can be bypassed by generating new keys outside of the YubiKey and importing them onto the device.

Question: where did security researchers find vulnerability ROCA IN October 2017?
the implementation of RSA keypair generation in a cryptographic library used by a large number of Infineon security chips