Microsoft Teams Vulnerability (CVE-2024-38197) Exposed Identity Trust Risks for 18 Months A critical vulnerability in Microsoft Teams (CVE-2024-38197) allowed attackers to spoof sender identities in chat messages, exploiting the trust employees place in familiar names and profiles. Disclosed by Check Point in March 2024, the flaw enabled threat actors to impersonate colleagues such as a CFO by altering the sender’s name in messages, creating a high-risk vector for wire fraud and social engineering in regulated industries like banking and finance. Microsoft did not fully patch the issue until October 2025, leaving over 320 million monthly active users exposed for 18 months. The vulnerability highlighted a broader weakness in identity verification within communication platforms, where even phishing-resistant MFA controls proved ineffective if the underlying identity layer was compromised. The flaw stemmed from insecure file and directory access in Teams, allowing attackers to manipulate trusted elements within the application. While a patch has since been released, the incident underscored the need for zero-trust governance in collaboration tools, including least-privilege access, verified identities, and out-of-band confirmation for high-stakes actions initiated via chat. Security teams were urged to update incident response playbooks to account for Teams-based compromises, as the attack surface extended beyond technical exploits to include trust-based social engineering. The case reinforced that cybersecurity defenses must address both system integrity and human psychology to mitigate modern threats.