CVE-2025-59252 – M365 Copilot Cloud Spoofing Vulnerability Closed

CVE-2025-59252 is a critical spoofing vulnerability in Microsoft 365 Copilot that Microsoft has already fully mitigated on the service side, requiring no customer action. Scored at CVSS 6.5 with critical impact on confidentiality, the flaw allowed remote attackers with network access to abuse user interaction flows to present spoofed Copilot content, potentially tricking users into disclosing sensitive information or acting on falsified AI output. While Microsoft rates exploitation as 'less likely' and reports no active exploitation, the issue highlights evolving risks where AI-assisted interfaces can be abused as trust anchors, aligning with MITRE ATT&CK T1204 (User Execution) and T1565 (Data Manipulation). The published vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N) underscores that an unauthenticated attacker could exploit the vulnerability over the network, but required user interaction to complete the attack chain. In practice, this could involve luring a user to a crafted link or workflow that causes Copilot to display spoofed content or misrepresented prompts under the guise of legitimate assistance. Although integrity and availability impacts are scored as none, compromise of confidential data surfaced or summarized by Copilot—including internal emails, files and tenant data—could be significant in real-world scenarios. For enterprises, the business impact of AI interface spoofing is less about direct system takeover and more about social-engineering amplification and data leakage. Users increasingly trust Copilot outputs embedded into Office apps and productivity workflows; a successful spoofing scenario can bypass traditional phishing skepticism by blending into familiar UI surfaces. This may trigger unauthorized sharing of confidential documents, copying of sensitive summaries, or execution of risky actions based on manipulated guidance, with knock-on consequences for GDPR and contractual confidentiality obligations. Microsoft notes that CVE-2025-59252 has already been fully remediated in the cloud service, with no patches or configuration changes required by customers. However, organizations should treat this as a signal to harden governance around AI copilots and chat interfaces by tightening data-access policies, limiting Copilot exposure to highly sensitive repositories, and updating security awareness training to cover AI-mediated phishing and prompt abuse. Continuous review of cloud service CVEs, particularly those rated critical or affecting confidentiality, should be integrated into SaaS risk management programs.