Italian activist David Yambio alerted the ICC that his phone was under surveillance while providing confidential information about torture victims in Libya.
The Citizen Lab confirmed Yambio was targeted by spyware while communicating with The Hague, with the attack occurring around June 2024.
Yambio urged ICC members to check their phones for spyware, raising concerns of interference in ICC proceedings involving torture victims.
The use of spyware has put pressure on Giorgia Meloni's government in Italy following previous revelations of surveillance targeting activists and journalists.
Osama Najim, wanted by the ICC for war crimes, was released by Italian authorities, sparking criticism over human rights violations in Libya.
The spyware used against Yambio and others was linked to an Israeli company, Paragon Solutions, now owned by a US investor.
WhatsApp disclosed that 90 users, including journalists and civil society members, were targeted by clients of Paragon, leading to scrutiny of the Italian government.
Paragon has suspended its contract with Italy due to alleged violations of rules against using spyware on journalists and civil society members.
Apple provided a fix for the security flaw exploited in the attacks on Yambio, highlighting the sophistication and high cost of the spyware.
The revelations have prompted questions about the deployment and use of spyware by various countries, with concerns raised about compliance with domestic laws.